2 beef tenderloin steaks (6–8 oz each, 1.5–2 in thick)
Salt and pepper
1 tbsp olive oil
2 tbsp unsalted butter
2 small shallots, finely minced
150 g (5 oz) mushrooms, sliced thin
1 clove garlic, minced
2 tsp Dijon mustard
2 tbsp Worcestershire sauce
½ cup heavy cream
1 tsp fresh parsley, chopped
Directions
Prepare the steaks: Pat steaks dry, season generously with salt and pepper.Heat 1 tbsp olive oil in a heavy skillet over medium-high heat until shimmering.Sear steaks 3–4 min per side for medium-rare (adjust for thickness). Remove to a plate and tent with foil.
Build the Diane sauce: Reduce heat to medium, add remaining 1 tbsp butter.Sauté shallots and mushrooms until softened and lightly caramelized, ~4 min.Add garlic, cook 30 sec until fragrant.
Flambé (optional) Remove pan from heat, add cognac, and ignite carefully, letting flames subside.If you prefer, skip flambé and just simmer for 1 min.
Finish the sauce Stir in mustard and Worcestershire.Add cream, simmer gently 2–3 min until slightly thickened. Taste and adjust seasoning.
Plate and serve. Pour sauce over steaks, sprinkle with parsley.
