- 3 tablespoons butter, divided
- 2 6-ounce beef tenderloin steaks (each about 1 inch thick)
- 1 3/4 cups 1/3-inch cubes peeled red-skinned potatoes (10 to 12 ounces)
- 1 1/2 cups chopped leeks (white and pale green parts only; about 2 medium)
- 1/2 teaspoon dry mustard
- 1 tablespoon steak sauce
- 2 large green onions, chopped
- 4 refrigerated pie crusts (two 15-ounce packages), room temperature
- 1 egg, beaten to blend (for glaze)
- Melt 1 tablespoon butter in medium skillet over medium-high heat. Sprinkle steaks with salt and pepper. Add steaks to skillet and cook until medium-rare, about 4 minutes per side. Transfer steaks to plate. Cut steaks into 1/2-inch cubes.
- Melt remaining 2 tablespoons butter in same skillet. Add potatoes, leeks, and dry mustard. Stir 1 minute. Reduce heat to medium, cover, and cook until potatoes are tender, stirring occasionally, about 8 minutes. Return beef and any accumulated juices to skillet. Add steak sauce and sauté 2 minutes. Remove skillet from heat. Mix in green onions. Season filling to taste with salt and pepper. Cool completely.
- Preheat oven to 400°F. Unfold crusts on work surface. Cut each crust into 2 pieces along center fold. Brush dough with egg. Place 1/2 cup filling on half of each piece. Fold plain dough over filling; seal edges. Brush pies with more egg; arrange on 2 baking sheets.
- Bake pies 15 minutes. Reverse sheets. Bake until crust is golden and filling is heated through, about 10 minutes.