Clean the mushrooms and fry them together with the onion in a little hot oil. Season with a little salt, pepper and rosemary and add a dash of soy sauce.
Meanwhile, dice the tomatoes and whisk the eggs, milk and parmesan together and also season with salt and pepper. Put the diced tomatoes in the pan and fry them briefly. Then add the egg-milk mixture to the pan and wait, stirring constantly, until the egg solidifies. Add the chives and season to taste.