Cook the noodles following package directions. Drain and set aside.

While the noodles are cooking, heat the olive oil in a large skillet over medium heat. Add the mushrooms and sauté until they are browned and tender. Remove and set aside.

Add the ground beef and onion to the skillet. Cook, stirring, until ground beef is no longer pink. Stir in the flour and cook, stirring, for 2 minutes longer.

Add the broth or water, the sauteed mushrooms, and the salt and pepper. Cook, stirring constantly, until hot and thickened.

Remove the pan from the heat and stir in sour cream.

Serve the stroganoff over the hot, drained noodles.