Finely dice the onion and cut the garlic very finely. Wash the zucchini, do not peel, but remove the seeds (otherwise it may water down), cut into very small cubes. Finely chop the parsley. Crumble the feta.
Place in a bowl with all the other ingredients and mix well. Shape meatballs out of it.
Let the oil get hot in a pan and fry the meatballs on medium heat for about 10 minutes on both sides.