bake.debo.lt — family recipes

Steps

Sear: Season the beef with salt and pepper. Heat the oil in a large skillet over high heat and sear the beef in batches, just until browned — don't cook through. Remove to a plate.
Tip: This is a quick sear, not a full cook. The beef finishes later, briefly, once it goes back in at the end.
Sauce: Add the butter to the pan, then the onion and mushrooms, cooking until the mushrooms have released their liquid and it's mostly cooked away.
Tip: Don't salt the mushrooms too early or crowd the pan — both encourage them to steam rather than brown.
Sauce: Add the garlic and cook briefly, then sprinkle the flour over and stir to coat everything.
Sauce: Whisk in the stock gradually, bring to a simmer, and cook until thickened.
Finish: Take the pan off the heat, or reduce to the lowest possible setting. Whisk a spoonful of the hot sauce into the sour cream to temper it, then stir the tempered sour cream and mustard back into the pan.
Tip: Off the heat and gradual — a hard simmer here will split the sour cream into curds and thin liquid, which can't be undone once it happens.
Finish: Return the seared beef to the pan just to warm through and finish cooking, about 71°C (160°F) if using ground beef, or to your preferred doneness if using sliced steak.