Beef Stroganoff

Beef

• 1.5 lb Sirloin or ribeye, thinly sliced
• 1 tsp Salt
• 1/2 tsp Black pepper
• 2 tbsp Neutral oil

Sauce

• 2 tbsp Butter
• 1 Onion, sliced
• 12 oz Mushrooms, sliced
• 3 cloves Garlic, minced
• 2 tbsp All-purpose flour
• 1 1/2 cups Beef stock
• 1 tbsp Dijon mustard
• 3/4 cup Sour cream

Sear

1. 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

1. 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.)
2. Add the garlic and cook briefly, then sprinkle the flour over and stir to coat everything.
3. Whisk in the stock gradually, bring to a simmer, and cook until thickened.

Finish

1. 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.)
2. 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.