Grind the leftover cold boiled beef and mix it in a bowl with a beaten egg, the finely minced garlic and the chopped parsley. Season with salt and freshly ground black pepper.
Wet your hands and shape the ground meat into balls not bigger than a walnut, roll them in breadcrumbs, then fry them in a large nonstick skillet with extra virgin olive oil. Turn the meatballs gently until they are golden brown on each side.
Transfer them to a sheet of kitchen paper and serve then with home made mayonnaise and mustard glazed carrots.