Filet Stroganoff
⏲ ~30 min total · prep 18 · cook 12 · 4 servings
Lunch⏱ 40 min total🔥 11.8g net carbs
By the KFI Test Kitchen · Tested & approved by Jason Lieu, KFI recipe editor
Published Sep 15, 2026 · Updated Sep 15, 2026
Ingredients
- 1 1/4 lb filet mignon, cut into 1-inch cubes
- 4 tbsp butter, divided
- 1 tsp avocado oil
- 10 oz cremini mushrooms, quartered
- 1 small shallot, minced
- 2 cloves garlic, minced
- 3/4 cup beef broth
- 1 tbsp Dijon mustard
- 1 tsp Worcestershire sauce
- 2/3 cup sour cream
- 1/4 tsp xanthan gum
- 10 oz frozen cauliflower rice
Instructions
- Blot the filet cubes dry on paper towels and season all faces with salt and pepper; moisture is the enemy of a crust.
- Heat a 12-inch cast-iron skillet over high until it just begins to smoke. Add 1 tbsp of the butter and the avocado oil, then sear the cubes in a single layer, in two batches so the pan never crowds, about 90 seconds per side to 125°F inside for medium-rare. Move them to a plate.
- Lower the heat to medium-high, melt 2 tbsp more butter, and spread the mushrooms in the pan. Leave them completely alone for 3 minutes until deeply browned underneath, then toss and cook 2 minutes more. Add the shallot for 3 minutes and the garlic for 30 seconds.
- Pour in the broth, scraping the fond loose, and boil 4-5 minutes until reduced by half. Whisk in the Dijon and Worcestershire.
- Pull the pan off the heat and whisk the sour cream with the xanthan in a small bowl, then stir it into the sauce. Return the filet with any resting juices and warm everything 1 minute over the lowest heat — boiling after the sour cream goes in will split the sauce.
- Meanwhile sauté the cauliflower rice in the last 1 tbsp butter in a wide skillet over medium for 6-8 minutes, stirring occasionally, until golden at the edges and no longer watery. Season with salt.
- Spoon the cauliflower rice into shallow bowls, pile the stroganoff alongside, and pour every drop of the mushroom sauce over the top.
Why this recipe works
- Filet, seared hard and fast Ninety seconds a side in a smoking cast-iron pan builds a crust while the cubes stay medium-rare at 125°F inside. Two batches keep the pan hot enough to do it again.
- Mushrooms left alone Quartered creminis spread in the pan and untouched for three minutes brown properly underneath. Stirred early, they steam gray and release their water.
- Sour cream off the heat The sour cream and xanthan go in after the pan leaves the burner, then one minute on the lowest heat to warm through. Boil it after that and the sauce splits.
Tips for making this recipe well
Blot the cubes twice
Surface moisture flashes to steam and blocks browning. Paper towels before seasoning, then again if the beef sits long enough to weep.
Pull at 125°F
The cubes climb a few degrees while they rest on the plate, which is what you want for medium-rare. Wait for 135°F in the pan and they land past medium.
Reduce before the dairy
Boiling the broth down by half concentrates it and builds body before anything delicate goes in. The Dijon and Worcestershire join during that reduction.
Xanthan into the sour cream first
Whisking the gum into the sour cream in a small bowl prevents the clumps that dry shaking causes. The sauce then thickens evenly as it warms.
Give the cauliflower rice color
Six to eight minutes in butter over medium brings golden edges and cooks off the package water. Pale rice reads bland next to a sauce this rich.
Serving suggestions
Spoon the buttered cauliflower rice into shallow bowls, pile the stroganoff alongside, and pour the mushroom sauce over everything without restraint; the recipe's own last instruction says every drop. Shallow bowls keep the sauce from sliding off a mound onto the counter. Each serving comes in at 11.8 net carbs, and the sour cream sauce is rich enough that a sharp green salad alongside earns its place. Serve the minute it leaves the pan, since the sauce thickens as it sits.
Storage and meal prep
The beef and sauce keep three to four days refrigerated in a covered container, and reheating wants a low hand: medium-low on the stove, stirred often, pulled as soon as it is warm through. A second boil after the sour cream is in risks splitting on day two as much as day one. The cauliflower rice keeps alongside and re-crisps in a dry skillet. Freezing holds for two to three months, though the dairy sauce can look grainy after thawing; a whisk over low heat usually settles it.
Variations worth trying
- Sirloin swap Sirloin cubes cost less and take the same sear; slice them against the grain to serve. Watch them a minute earlier, since sirloin tightens faster past medium-rare.
- More mushrooms A second 10-ounce package of creminis stretches the sauce into more of a mushroom dish. Brown the second batch separately so the pan stays hot.
- Extra Dijon A second tablespoon of Dijon pushes the sauce sharper, closer to the old bistro versions. Add it with the broth rather than at the end.
- Noodle-style base Shirataki fettuccine replaces the cauliflower rice for a closer nod to the classic plate. Rinse and dry-sauté them before they meet the sauce.
Frequently asked questions
Can I use a regular skillet instead of cast iron?
A heavy stainless pan works; thin nonstick struggles to hold the heat for a hard sear. Preheat whichever you use until it starts to smoke.
Why 125°F for the beef?
That is medium-rare for beef, and the cubes gain a few degrees as they rest on the plate. The sear-and-rest plan in the recipe is built around that finish.
My sauce split. Can it be saved?
Off the heat, whisk in a spoonful of cold sour cream and keep the pan below a simmer from there. Prevention is easier, so no boiling once the dairy goes in.
Can I leave out the xanthan gum?
Yes, and the sauce runs thinner. Reducing the broth further before the sour cream goes in, or simmering a minute longer at the end, gets close to the same body.
How do I get the cauliflower rice golden?
A wide skillet, medium heat, and no stirring for the first few minutes. Contact with the pan is what browns it, and crowding steams it instead.
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