Prepare the "trito", i.e. chopped carrots, onion and celery. Half of it will be part of meatballs mix, remaining will be used to prepare the sauce.
Mix the ingredients in a bowl: the minced beef, the egg, the bread crumbs, the dried onion, the dried garlic, the parsley, the tomato concentrate, the vinegar, salt and black pepper.
Add half of the trito.
Work by hand the ingredients until you obtain a well formed meatloaf (see video below). Cover it and let it rest while you prepare the sauce.
Use peeled tomatoes to prepare the sauce, since they give the best results. You will need to mix them to obtain a sauce.
In a pan, gently fry the remaining trito in extra virgin olive oil, and when it's ready (see picture) add the tomato sauce. When it starts boiling, it is ready for the meatballs.
Prepare the meatballs (the size of a large walnut) and drop them into the boiling sauce. It should be enough to cover them. Let them cook at low heat, covered, for about 1 hour and a half, adding a pinch of salt and oregano, according to taste. And.. enjoy!