A winner! Simple to make, great tasting, and very attractive, too.
In a large skillet, melt the margarine over medium heat. Add the onion, pepper, and mushrooms and saute until soft but not brown, about 5 minutes. Add the tomatoes, basil, and dill and cook for 2 minutes. Season the sour cream with the salt and pepper. Stir the sour cream into the vegetables gently but thoroughly. Serve at once.