It's an old old dish, often prepared in the past in the countries of Italy from North to South, it's made with simply and cheap ingredients that every family could afford.
Nowadays it could be a complete meal served with fresh salad and tomatoes or an informal appetizer if cutted in tiny blocks sticked on a toothpick.
6-8 egg for 6-8 for 4-5 persons
a nut of butter
salt and pepper
3 little red onions
2 tablespoons of water
2 tablespoons of extravirgin olive oil
3 tablespoons freshly grated parmesan
Put in a pan the butter, turno on medium heat, cut in very thin slices the onions then put them in the pan.
Let them stir-fry, add a little water if needed, when they are soft and golden let them warm.
In a bowl beat eggs with salt, pepper and parmesan.
Put another pan on the fire with extravirgin olive oil, add onions to the bowl with eggs, mix then pour in the hot pan: shake a little to let the mixture spread, cover with a lid, turn the fire to light then wait.
When the omelette is solidified you have to turn it on the other side: how it's up to your ability...
If you're a good at you can rotate it in the pan with a good wrist movement, if you're like me (not so skilled in acrobatic cooking) put a dish on the omelette, keep it firmly then turn the pan.
Now the omelette is on the dish upside down, let it slip in the pan once again, add a little more oil if needed, finish the cooking.
If you want to cut the frittata let it get cold, if not you can serve it hot or warm, as you like.
Frittata, like omelette, is a versatile food: the one with onions is typical here but not the only one.
You can add mozzarella cheese cubes, chopped stirfried bacon or ham, stuffed broccoli, stirfried courgettes or leeks, sausage and everything you want.
If sometimes any pasta left from a lunch or a dinner, the next meal often present a "frittata di pasta " (pasta omelette): with the same procedure just add the pasta left (spaghetti are the best) mix well with the egg mixture then pour in the pan.