Preheat the oven to 200 degrees Celsius/ 400 degrees Fahrenheit. Line one or two baking trays with parchment paper.
Grate the zucchini finely and squeeze out excess liquid. Don't overdo it, you still want to have some moisture, just squeeze lightly to remove what is too much.
Grate the onion and the garlic cloves finely as well. Grate the Parmesan. Chop the dill finely. Remove the crust from the bread slice and crumble the bread with your fingers to obtain crumbs. Beat the eggs lightly.
Place the beef, zucchini, onion, garlic, Parmesan, dill, breadcrumbs, and eggs in a bowl. Add salt and pepper generously and mix everything with your hand. Add some more salt and pepper to taste.
Form the meatballs, I had 35 medium ones. Press them a little flat with your hand.
Heat one tablespoon vegetable oil in a large skillet and start frying the meatballs, about 2 minutes on each side, in batches. As they are ready, transfer them to the prepared trays. Add another tablespoon oil in the skillet, if necessary, and continue the process with the rest of the meatballs.
Bake the meatballs for 7 or 8 minutes. Serve as suggested above.