First, make the tomato sauce. Heat the oil in a large sauté pan or shallow casserole over a medium heat. Add the onion and a good pinch of salt and gently fry for five to 10 minutes until softened. Add the garlic and fry for two minutes, then stir in the tomato purée and paprika and cook for another two minutes.
Tip in the tomatoes and chopped basil, then gently simmer for 20 minutes. Taste to check the seasoning, adding salt, pepper and a little sugar to balance the acidity of the tomatoes if needed.
Meanwhile, make the meatballs. Place the breadcrumbs in a large mixing bowl and pour over the milk. Add the turkey, garlic, lemon zest, egg, cheese, oregano, nutmeg, salt and a good grinding of black pepper. Using your hands, gently combine, taking care not to overmix. With wet hands, gently shape the mixture into about 20 small-medium meatballs (about the size of golf balls – roughly 40g each and 5cm in diameter).
Gently drop the meatballs into the simmering sauce, cover with a lid and simmer for 20 minutes, turning them after about 10 minutes and giving the pan a shake from time to time.
Remove the lid and simmer for another five minutes. Serve the meatballs with the basil leaves and a grating of pecorino or Parmesan.