Serving suggestion. Nutrition is approximate.
Equipment
- Wide skillet
- board
- knife
- bowl and thermometer.
Before you begin
US cup = 240 ml; tablespoon = 15 ml; teaspoon = 5 ml. Use listed gram weights for consistency; weights are raw or dry unless described as cooked or drained.
- Use tender strip steak instead of sirloin; slice across the grain.
Make it work
- Choose sirloin or another tender steak cut; this is not a slow braise.
Prep 20 min · Cook 25 min · Waiting 3 min
Serves 4 / Prep 20 min / Cook 20-25 min / Rest 3 min. Times are estimates; chilling and resting are included in total time.
Ingredients
- 650 g / 22.9 oz Beef sirloin steak, trimmed
- 250 g / 8.8 oz Cremini mushrooms, sliced
- 150 g / 5.3 oz Onion, thinly sliced
- 20 ml / 0.7 US fl oz Sunflower oil
- 20 g / 0.7 oz Unsalted butter
- 10 g / 0.3 oz All-purpose flour
- 200 ml / 6.8 US fl oz Low-sodium beef stock
- 150 g / 5.3 oz Full-fat sour cream, 20% fat
- 1 tsp / about 5.0 g Dijon mustard
- 3/4 tsp, divided / about 4.5 g Fine salt
- 1/2 tsp / about 0.9 g Black pepper
- 5 g / 0.2 oz Fresh parsley, chopped
Step-by-step method
- Slice across the grain
Chill steak briefly for easier slicing. Cut across the muscle grain into strips about 5 mm / 1/4 inch thick and pat dry. Keep refrigerated until cooking. Mix sour cream and mustard in a bowl; use full-fat sour cream to reduce curdling. - Sear in small batches
Heat oil in a wide skillet over high heat. Season beef with half the salt and sear in two or three uncrowded batches, about 45-60 seconds per side. Remove to a plate promptly; cooking all the meat in one crowded pan makes it steam. - Cook the vegetables
Reduce to medium. Add butter and onion to the same pan and soften 5 minutes. Add mushrooms and cook 6-8 minutes until their liquid evaporates and the edges color. Scrape up browned juices without burning them. - Build the sauce
Sprinkle flour over vegetables and stir 1 minute. Pour in stock gradually, stirring out lumps. Simmer 3-4 minutes until lightly thickened. Add remaining salt and pepper, tasting before adding extra salt to a purchased stock. - Temper the sour cream
Turn heat to low. Stir several spoonfuls hot sauce into the sour cream mixture, then fold it into the pan. Keep below a boil so the dairy stays smooth. Return beef and collected juices only once the sauce is ready. - Finish briefly and serve
Warm beef gently 1-2 minutes. Check the thickest strip reaches at least 63 C / 145 F, then rest off heat 3 minutes. Scatter parsley and serve promptly. Prolonged simmering tightens this tender cut; rice, noodles or mash are separate accompaniments.
Cook’s notes
Choose sirloin or another tender steak cut; this is not a slow braise.
Storage & reheating
- Refrigerate within 2 hours (1 hour above 32 C / 90 F) in a shallow covered container at 4 C / 40 F or colder. Use within 3 days.
Allergens
milk, mustard, wheat/gluten. Check labels on packaged ingredients and any substitutes.
Approximate nutrition
Per serving: 524 kcal · Protein 37 g · Carbohydrates 11 g · Fat 37 g.
Approximate per serving of the complete recipe. Brands, substitutions, cooking losses and portion sizes affect the figures.
