First peel the onion and garlic, chop and sweat in a little olive oil until translucent. Then add tomato paste and tomatoes and sauté briefly. Now add the rest of the ingredients except for the mozzarella and cook for about 10 to 15 minutes. As soon as the liquid can no longer be seen, add the mozzarella. Heat on a low flame and stir in until melted. Season with Italian herbs if necessary. Serve immediately.