reserved gravy from Coriander-Dusted Roast Beef or other gravy
roast beef, sliced 1/4 inch thick and cut into strips or half of the Coriander-Dusted Roast Beef
buttered noodles, for serving
In a large skillet, heat the olive oil until shimmering. Add the onion, mushrooms and thyme, season with salt and pepper and cook over moderate heat, stirring occasionally, until tender and browned, 8 minutes. Add the gravy and bring to a boil. Stir in the sour cream. Add the beef and simmer until heated through, about 2 minutes. Serve over buttered noodles.