Cook the potato in a pot with plenty of salt water. The time will depend on how big it is, in our case it took 45 minutes. If you are in a hurry you can use small potatoes and save yourself some time.
When it is tender inside, remove the potato from the water and we peel hot. Crush with a fork, add the grated Parmesan cheese, a pinch of nutmeg and season to taste. We booked.
We peel and finely chop all vegetables (zucchini can be left unpeeled). We are poaching them in a pan with olive oil in order of hardness. We start with the onion and the garlic clove. When they are tender we add the carrot and then the zucchini.
Add the poached vegetables to the potato, along with a couple of tablespoons of the egg (we reserve the rest for breading) and the finely chopped fresh parsley. Season to taste. Mix well to obtain a homogeneous dough.
We form the meatballs, pass them through beaten egg and breadcrumbs and fry them in a pan with abundant oil vegetable. We let the excess oil drain on absorbent paper and ready to serve.