BEEF STROGANOV
Source: Sara Moulton

2 tablespoons unsalted butter, divided
1/2 tablespoon all-purpose flour
1/2 cup beef broth
1 (1/2 pound) piece beef tenderloin, trimmed, sliced 1/4 inch thick, then cut into 1-inch pieces
1 tablespoon olive oil, divided
1/4 cup thinly sliced shallot
1/2 pound cremini mushrooms, trimmed and halved (quartered, if large)
2 tablespoons sour cream, at room temperature
1/2 teaspoon Dijon mustard
1 tablespoon chopped fresh dill
1/4 teaspoon salt
1/8 teaspoon black pepper
Accompaniment: buttered cooked wide egg noodles

Melt 1 tablespoon butter in a small heavy saucepan over moderate heat and whisk in flour, then cook roux, whisking constantly, 2 minutes.

Add broth in a slow stream, whisking constantly, and bring to a boil. Reduce heat and simmer, whisking occasionally, 3 minutes. Remove from heat and keep warm.

Pat beef dry and season well with salt and pepper. Heat 1/2 tablespoon butter with 1/2 tablespoon oil in a 12-inch heavy skillet over moderately high heat until foam subsides. Saute beef turning once, until browned on both sides but still pink inside, about 1 minute. Transfer to a plate with a slotted spoon.

Heat remaining 1/2 tablespoon butter with remaining 1/2 tablespoon oil in same skillet over moderately high heat until hot but not smoking, then saute shallot, stirring occasionally, until golden brown, about 3 minutes.

Add mushrooms and saute, stirring occasionally, until the liquid mushrooms give off is evaporated and mushrooms are browned, about 8 to 10 minutes.

Return meat with its juices to skillet, stir to combine, and then transfer to a platter.

Reheat sauce over low heat (do not let boil), then whisk in sour cream, mustard, dill, salt, and pepper.

Pour sauce over beef and serve immediately.