Make the panade: In a large bowl, combine gluten free breadcrumbs and milk. Stir and let it sit for 3–5 minutes until it looks like a thick paste.

Add aromatics and seasonings: Mix in the egg, grated onion (and its juices), garlic, Parmesan, parsley, salt, pepper, oregano, and red pepper flakes. Stir until smooth.

Add the meat: Break the ground beef and pork into chunks and add to the bowl. Gently mix with your hands or a fork until just combined. Do not overmix—stop as soon as it looks uniform.

Shape: Lightly oil your hands. Scoop about 2 tablespoons per meatball (golf ball size) and roll gently. You should get about 20–24 meatballs.

Chill briefly: Place the meatballs on a parchment-lined tray and refrigerate for 10–15 minutes. This helps them firm up for better browning.

Brown the meatballs: Heat 2 tablespoons olive oil in a large skillet over medium heat. Add meatballs in a single layer without crowding. Sear 2–3 minutes per side until browned. Transfer to a plate and repeat with remaining meatballs, adding more oil if needed.

Simmer in sauce: Pour marinara into the skillet. Nestle the browned meatballs into the sauce, cover, and simmer gently over low heat for 12–15 minutes, or until cooked through (160°F/71°C internal temperature).

Taste and finish: Taste the sauce and adjust salt or pepper if needed. Sprinkle with extra parsley and Parmesan to serve.