For the tomato dumplings with arugula, first prepare the dough. Mix egg, oil, tomato paste and salt, add mineral water. Mix flour and cornmeal. Let the dough stand for at least 30 minutes.
Rub the dough with a dumpling grater into boiling salted water and boil briefly, then strain.
In a frying pan, sauté the finely chopped onion in oil until translucent. Chop the bell pepper and pepperoni and sauté.
Beat the eggs, add to the pan and season with salt.
Add the finely chopped arugula to the egg mixture just before serving and sauté briefly with the dumplings.
Serve the tomato dumplings with arugula hot.