Heat olive oil in a pan and fry the finely chopped meat in it. Add the chopped onion and once braised, add the tomatoes, finely chopped, mushrooms and crushed garlic.
Season with salt and black pepper and add the pitted olives, and 2/5 cup (100 ml) of water. Allow to come to a boil, wait for the water to evaporate and let the dish remain mostly in fat.
If you wish, you can add chili peppers, to get a spicy twist.