Preheat the oven to 400°F (200°C). Line a rimmed baking sheet with parchment for easy cleanup, or lightly oil it to prevent sticking.
Mix the flavor base. In a large bowl, combine grated onion (and its juices), garlic, parsley, Italian seasoning, smoked paprika, salt, and pepper.
Stir to distribute the seasoning evenly.
Add the binders. Crack in the egg and whisk it into the onion mixture, then sprinkle in the breadcrumbs. Let it sit 1 minute so the crumbs hydrate.
Fold in the turkey gently. Add the ground turkey and mix with a fork or your hands just until combined. Don’t overwork it or the meatballs will be tough.
Shape the meatballs. Lightly oil your hands, then roll into 18–20 balls, about 1 to 1.25 inches in diameter (roughly 1.5 tablespoons each).
Place on the prepared sheet, leaving space between them.
Lightly brush or mist with oil. This helps browning without adding many calories.
Bake for 13–16 minutes. They’re done when the centers reach 165°F (74°C) and the exteriors look set and lightly golden.
Optional: Broil 1–2 minutes. For extra color, broil on high at the end, watching closely to avoid burning.
Rest and serve. Let the meatballs rest 3 minutes. Squeeze with lemon and sprinkle more parsley if you like.