Prep the aromatics. Grate the onion on the small holes of a box grater over a bowl to catch the juices. Mince the garlic. This step is key for juicy meatballs without big onion chunks.

Mix the meatball base. In a large bowl, combine turkey, grated onion and juices, garlic, breadcrumbs, parmesan, egg, parsley, salt, pepper, Italian seasoning, and red pepper flakes. Use your hands or a fork to mix just until combined. Do not overmix, which can make meatballs tough.

Form the meatballs. With damp hands or a small scoop, roll into golf ball–sized meatballs (about 1.5 inches). You should get 20–24 meatballs. Place them on a parchment-lined sheet pan.

Choose your cooking method. You can sear on the stovetop for extra flavor or bake for convenience: To sear: Heat 2 tablespoons olive oil in a large skillet over medium heat. Add meatballs in batches and brown on all sides, 5–7 minutes total. They don’t need to cook through yet.

To bake: Brush or mist meatballs with olive oil. Bake at 400°F (200°C) for 12–14 minutes until lightly browned and almost cooked through.

Simmer in marinara. Pour marinara into a large skillet or pot and bring to a gentle simmer. Nestle the browned or baked meatballs into the sauce. Cover and cook on low for 10–15 minutes, until the meatballs are fully cooked (internal temp 165°F/74°C) and infused with sauce.

Taste and finish. Adjust salt and pepper in the sauce if needed. Sprinkle with chopped basil or extra parsley. If the sauce seems too thick, add a splash of water or chicken broth to loosen.

Serve. Spoon over pasta, zoodles, or spaghetti squash, or pile into toasted hoagie rolls for a meatball sub. Add more parmesan if you like.