Greek Herbed Meatballs (Keftedes) Pre-heat your oven to 350°. Grate or finely chop onion and add it to a mixing bowl. Finely chop or grate garlic and add it to the mixing bowl. Chiffonade mint and put in the mixing bowl. Chop parsley and add it to the bowl. Put beef, bread crumbs, egg, parsley, oregano, pepper, and vinegar in the mixing bowl. Combine. Portion meatballs out onto a baking sheet lined with parchment paper or aluminum foil. Bake meatballs for 20 minutes.