How to make
Peel the mushrooms and onions.
Cut the onion into small cubes and the mushrooms into thin slices. Heat olive oil in a pan on a heated hob at a moderate temperature.
Add the onion and fry it for about 5 minutes until it softens.
Add the mushrooms and fry them for another 10 minutes. Season with oregano, black pepper and salt.
Add the tomato sauce and leave the dish fry for another 10 minutes, while stirring occasionally.