Beef Stroganoff

My note: imported from RecipeTin Eats — tweak to match what I actually do.

Preparation

1. Flatten the steak to about ¾ cm thick and slice into 5 mm strips. Season with salt and pepper.
2. Heat 1 tbsp oil in a large skillet over high heat. Sear half the beef, ~30 seconds per side, until browned; set aside (pink bits are fine). Repeat with the remaining oil and beef.
3. Reduce to medium-high. Melt the butter, cook the onions 1 minute, then add the mushrooms and cook until golden, scraping the pan.
4. Stir in the flour for 1 minute. Gradually add the broth while stirring, then the sour cream and mustard until smooth.
5. Simmer until the sauce thickens to a pouring-cream consistency (3–5 minutes). Season with salt and pepper.
6. Return the beef and juices, simmer 1 minute, and remove from the heat right away.
7. Serve over pasta or noodles, with chives if you like.