Mushroom Strogonoff with Cashew Cream

What it is

White button mushrooms, browned hard in two batches and folded into a sauce built the way Panelinha builds its estrogonofe, on tomato paste and a spoon of ketchup, with a little mustard from me. Where the classic pours in creme de leite, this one pours in cashew cream: raw cashews soaked in just-boiled water, then blended smooth with lemon and a pinch of salt. White rice beside it, toasted cashews on top for the crunch.

Panelinha files its estrogonofe under Russian, practical and classic cooking all at once, and serves it with white rice and batata palha, those crispy potato sticks. Mine has no meat at all: the mushrooms do the chewing and the cashews do the cream. I'm lacto-vegetarian, so this is a plate I actually eat, and it happens to have no dairy in it either.

It's also Protein Champion number eleven. Embrapa, Brazil's agricultural research agency, traces the cashew tree to tropical America, with its greatest variety along the coast of Brazil's Northeast, among the beaches, dunes and restingas (sandy coastal scrub), where the region's Indigenous peoples were already using it when the first colonisers wrote it down. More than 98% of Brazil's cashew-growing area is in the Northeast. The nut has a protein story worth a whole plate, plus an honest twist.

Why you should eat it

Here's the short version, before the snack aisle claims cashews for good. USDA FoodData Central lists 18.2 g of protein per 100 g of raw cashews, with 3.3 g of fiber in that same 100 g, and most of this pan's cashews go into the cream. The mushrooms chip in too: 3.09 g of protein and 1.0 g of fiber per 100 g of raw white mushrooms, same database. Now the honest part. Cashews are mostly fat, 43.8 g per 100 g, with 7.78 g of it saturated, so this is a rich sauce, and the rice brings most of the carbs. The card below adds up the whole plate, and on protein it's modest for a champion, with the cashews carrying the biggest share. I'd rather tell you than dress it up. A ladle of feijão beside it changes the picture, and I'll show you why while the sauce simmers.

Tips

• Just-boiled water is the fast route: Plantte gives cashews 10 to 30 minutes that way, and in this method they get a little longer while you cook. No kettle handy? Plantte's slow route is a 4-hour soak in cold water. Either way the soak water goes down the sink, and the cream gets fresh water, the same volume as the dry cashews, for a thick result.
• Mushrooms in two batches, one layer each. Crowd the pan and they steam instead of browning. The salt waits for the sauce.
• Buy the mushrooms already sliced and the prep drops by about 6 minutes.
• Training week tip: blend a double batch of cashew cream on Sunday. It keeps about 5 days to a week in a sealed jar in the fridge (Plantte), so Wednesday's strogonoff skips the soak and the blender.
• Packing it for lunch? Keep the toasted cashews in a little pot of their own so they stay crunchy. Panelinha does the same with the batata palha when estrogonofe goes in a lunchbox.
• Best teammate: a ladle of feijão alongside, Champion number one's black beans for example. It brings the lysine ('While it simmers' has the arithmetic). It isn't on the nutrition card, so the card shows the strogonoff and rice alone.
• This dish contains tree nuts, in the sauce and on top. If anyone at your table has a nut allergy, it isn't for them as written. See the swaps.

Substitutions

• Toasted cashews on top: Batata palha, the way Panelinha serves estrogonofe The classic crunch. The card is built on cashews, so it won't match, and the protein drops.
• White button mushrooms: Part shiitake USDA FoodData Central lists 2.24 g of protein and 2.5 g of fiber per 100 g of raw shiitake (record 169242), against 3.09 g and 1.0 g for raw white mushrooms. The card is built on white mushrooms, so it won't match.
• Raw cashews for the cream: Roasted unsalted cashews A stronger, toastier cream (Plantte). The card is built on the raw cashew record, so it won't match exactly.
• Cashew cream, for a tree nut allergy: Creme de leite, as in Panelinha's classic estrogonofe, with batata palha on top in place of the cashews It becomes the classic dairy strogonoff and stops being this Protein Champion. The card won't match.

Storage

Leftover strogonoff: cool it and get it into the fridge within one to two hours, eat it within 48 hours or freeze it, and reheat it only once (UK Food Standards Agency). Rice: chill leftovers as fast as you can, ideally within an hour, keep them no more than a day, and reheat them until steaming hot all the way through (Food Standards Agency again). The cashew cream on its own keeps about 5 days to a week in a sealed jar in the fridge; it may thicken or separate, so give it a shake (Plantte).

While it simmers: who's lending the scissors

Sauce on low, spoon in hand, five minutes to spare. Let's talk about what's in that cream.

Protein is a chain built from amino acids, and nine of them your body can't make, so they have to come from food. The internet loves ranking nuts by grams of protein and stopping there. The mix is the interesting part, and two amino acids keep coming back in this series: lysine, and the sulfur pair, methionine and cysteine.

In USDA FoodData Central's record for raw cashews, lysine makes up 5.10 g of every 100 g of protein, and the sulfur pair 4.15 g. Cooked white rice, for comparison: 3.61 g of lysine per 100 g of its protein. The FAO's 2013 expert report sets a reference for older children, teenagers and adults: 4.8 g of lysine and 2.3 g of the sulfur pair per 100 g of protein. On paper, cashew protein clears both. Of the five nuts I looked up in that database, cashews had the biggest sulfur-pair share and the second-biggest lysine share, behind pistachios.

Here's the picture I'd draw for a class. Craft table: every card needs a pair of scissors and a glue stick. Thirty glue sticks and ten pairs of scissors finish ten cards, and the extra glue just waits. On this plate, lysine is the scissors and the sulfur pair is the glue.

Rice (3.61) and mushrooms (3.46) bring about as much protein as the cashews do, with fewer scissors, so by my arithmetic the three main protein carriers land at 4.31 g of lysine per 100 g of protein, a little under the 4.8 line. Without the cashews it would be 3.53. Here, the cashew is the one lending.

Now the teammate. Cooked black beans carry 6.86 g of lysine per 100 g of protein and only 2.58 g of the sulfur pair, the part cashews have plenty of. Add a ladle of feijão, 150 g a plate, and the plate climbs to 5.48 g of lysine and 3.03 g of the sulfur pair, both over the adult line. Champion number one, back for a guest set.

The picture stops in two places. Every pair of scissors on a craft table works, but digestion takes its cut from food, and these shares are counted before it does; the FAO's own scoring corrects for that, and mine doesn't. And the FAO's stricter pattern for young children, 5.7 g of lysine, the one it recommends for regulating foods, leaves cashew protein (5.10) a little short.

So, in one line: cashews bring plenty of the sulfur pair and a decent share of lysine, and a ladle of beans covers what the rice and mushrooms leave open.

Case one: what the label promises and what you keep

Eighteen healthy adults near Washington DC, nine men and nine women, average age about 57, ate every meal from the USDA's Beltsville Human Nutrition Research Center for two 4-week stretches. Same base diet both times, but in one stretch 42 g of cashews a day went in, half at breakfast and half at dinner, with the other foods trimmed so the energy matched. In the last week of each stretch, everyone collected all their urine and stool, and the lab measured what had passed through unused. Not the glamorous side of science.

The label math is a century-old system called the Atwater factors, and the authors think it overestimates how well we digest nuts. Earlier work the authors cite found whole nut cells travelling all the way through, fat still locked inside. The real number: a 28 g serving gave these people 137 kcal on average, against 163 on the label and in USDA's database, 16% less. Person to person it ran from 105 to 151, so even the highest stayed under the label. Protein in the whole diet was still 90.1% digested with the cashews, against 91.2% without.

For your plate: whole cashews give you a little less energy than the packet says, and the protein in that diet was still mostly digested.

Where it stops: one dose, whole nuts, no cream. The same team found that roasting almonds and blending them into butter raised the energy people absorbed, because smaller pieces break more cell walls. My hunch, and only a hunch: this smooth cream gives up more than whole cashews would. Nobody has tested that for cashews. The paper doesn't say whether its cashews were raw or roasted. The USDA and the Global Cashew Council paid for it, and the authors declare no conflict of interest.

Case two: a cashew protein drink against whey

Researchers at the Universidade Federal de Viçosa, in my home state of Minas Gerais, worked with Embrapa's tropical agroindustry unit in Fortaleza to build a high-protein drink from what's left after cashew processing: partly defatted cashew cake and a cashew protein concentrate. Eighty-one tasters picked the best of three versions, and vanilla won. That drink carried 35.39 g of protein per 400 mL.

Then 27 healthy people tried it in a randomized, blinded crossover trial. On separate occasions, each one drank the cashew drink, a whey protein drink and a cow's milk drink, all three matched for energy and nutrients. They rated how full they felt, recorded what they ate afterwards and answered questions about their gut.

The result: no significant difference between the three drinks in fullness, in what people ate next, or in gut symptoms.

For your plate: cashew protein held its own against whey, the gym shelf's favourite, on fullness in this one test.

Where it stops: this was a drink made from a concentrate of cashew leftovers, not whole cashews or a homemade cream, and one sitting per drink. The full paper sits behind a subscription wall, so I've read only its summary. That means I can't tell you the ages, the split of men and women, the authors' own limits or their conflict statement, and the summary gives no amino acid numbers for the drink. Brazilian public research bodies (CAPES, CNPq, FAPEMIG and Embrapa) funded it, and one author works at Embrapa. A promising first look, and only a first look.

Case three: cashews and cholesterol, a split decision

Two tightly controlled US feeding trials, where the researchers supply the food, asked the same question and got different answers.

The first is the parent trial of case one: 42 adults, two 4-week stretches on the same diet, one of them with 42 g of cashews a day and the other foods trimmed so the energy matched. No significant differences in blood fats, blood pressure or blood sugar. One protein tied to how the body handles cholesterol, PCSK9, did fall, while LDL itself held still.

The second fed 51 men and women aged 21 to 73, median LDL 159 mg/dL at screening, a typical American diet for 28 days with cashews (28 to 64 g a day) and 28 days with potato chips instead. Against the chips, cashews came out ahead: median LDL down 4.8% against up 1.2%, total cholesterol down 3.9% against up 0.8%. HDL and triglycerides didn't differ.

The label twist: in the US, the FDA's qualified health claim for tree nuts leaves cashews out because of their saturated fat. How much of that fat is stearic acid, the kind both teams call neutral for blood lipids, depends on who you ask: mostly, say the first trial's authors; about a third, say the second's.

For your plate: don't count on cashews to move your cholesterol. Two careful trials split on it.

Where it stops: both ran four weeks, and both full papers sit behind a bot check I didn't get past, so I've read only their summaries. The first was part-funded by the Global Cashew Council; in the second, the trial's registration (NCT02769741) names The Kraft Heinz Company as lead sponsor, and one author worked there. Between us, and this part is my opinion: potato chips make an easy opponent. If you're managing your cholesterol, your doctor is the right person to weigh this.

Case four: a weight-loss trial in Viçosa, Minas Gerais

Back to Viçosa for the longest test here. The Brazilian Nuts Study gave adults aged 20 to 55 living with overweight or obesity, average age 33, a personal diet planned at 500 calories a day under their needs. Of 98 randomized, 74 finished; 6 who gained weight were left out, leaving 68. For 8 weeks, one group added 30 g of cashews a day as a mid-morning snack, one added 30 mL of cashew nut oil, and one had no nuts, olive oil or avocado.

All three groups lost body fat (3.1 kg without nuts, 3.3 kg with cashews, 1.8 kg with the oil) and weight (4.2, 3.9 and 3.4 kg), with no differences between them. Inside the cashew group, some blood numbers moved: apoB down 6.6 mg/dL, triglycerides down 30.9, total cholesterol down 13.8, and the count of people with obesity fell from 19 to 13. None of those beat the no-nut group, and the cashew group's LDL didn't move significantly.

For your plate: a daily handful of cashews fit inside a calorie-cut diet without slowing the fat loss.

Where it stops: every change was inside a group, nothing differed between groups, and the authors write that their body-fat hypothesis wasn't confirmed. Eight weeks is short, and the real energy cut came out at about 205 calories a day, not 500. And I'd say leaving out the 6 who gained weight makes the groups look tidier than real life. Embrapa donated the nuts and the oil and employs one author; CAPES, CNPq and Fapemig funded the rest. If you're working on your weight with a doctor or dietitian, bring this to them.