Peel the mushrooms and onions, chop. Slice tomatoes and peppers.
In a large frying pan, heat the olive oil, fry the onions, then add the mushrooms and tomatoes and pepper.
Reduce heat and simmer for about 20 minutes under the lid, remembering to stir. At the end of cooking, salt, pepper, add basil and mix.
This stew can be served with rice or pasta, sprinkled with grated cheese on top of a hot dish.