2 tablespoons olive oil
4 (5 to 6-ounce) tail of filet or filet mignon pieces, cut crosswise into 1/4-inch-thick pieces
2 tablespoons unsalted butter
1 1/2 cups finely chopped onion
Salt and freshly ground black pepper
1/2 pound fresh shiitakes, stems discarded and caps thinly sliced (about 2 cups)
1/2 pound white mushrooms, trimmed and thinly sliced (about 2 cups)
2 tablespoons all-purpose flour
1 cup dry red wine
1 1/2 cups beef broth
1/2 cup sour cream
1 tablespoon Worcestershire sauce, or to taste
1/4 cup finely chopped fresh parsley leaves
Serving Suggestion:
buttered egg noodles

In a 10 to 12-inch skillet heat 2 tablespoons oil over moderately high heat and brown beef in batches, transferring beef to plate with slotted spoon or tongs.

Add 2 tablespoons butter to skillet and cook onion with salt and pepper, to taste, over moderate heat, stirring, until softened. Add mushrooms and cook, stirring, until tender and liquid they give off is evaporated. Sprinkle flour over vegetables and cook, stirring 1 minute. Add wine and boil until cooking liquid is almost evaporated Add broth and simmer 1 minute. Stir in sour cream and Worcestershire sauce.

Return beef to skillet and gently simmer carefully, stirring occasionally, until beef is warmed through about 3 to 5 minutes. Stir in parsley, and season with salt and pepper, to taste.

Serve stroganoff with buttered noodles.