Prep the vegetables. Grate the zucchini and carrot on the small holes of a box grater. Grate the onion as well.
Squeeze the zucchini firmly in a clean towel to remove extra water. This step prevents soggy meatballs.
Mix the base. In a large bowl, combine the ground meat, grated veggies, garlic, breadcrumbs, Parmesan, egg, parsley, salt, pepper, and paprika. Use clean hands to mix gently until just combined.
Don’t overwork it.
Form the meatballs. Scoop 1 1/2 tablespoons per meatball and roll lightly with damp hands. You should get about 20–24 small meatballs. Place them on a parchment-lined baking sheet.
Bake for even cooking. Bake at 400°F (200°C) for 12–15 minutes, until the centers are just cooked through and the edges are lightly browned.
For extra color, broil for 1–2 minutes at the end.
Or pan-sear for a crust. Heat a slick of olive oil in a large skillet over medium heat. Brown meatballs on all sides, about 6–8 minutes total, then simmer in marinara for 5 more minutes to finish cooking.
Serve your way. Toss with warm marinara and pasta, spoon over polenta, slide into a toasted sub, or serve with rice and roasted broccoli. A sprinkle of extra Parmesan never hurts.