In a large mixing bowl, combine the ground turkey, grated apple, chopped sage, breadcrumbs, Parmesan cheese, egg, minced garlic, onion powder, salt, and black pepper.
Mix all the ingredients with your hands or a spoon until just combined. Avoid overmixing, which can make the meatballs tough.
Form the mixture into small meatballs, about 1 inch in diameter. You should yield around 20 meatballs.
Heat the olive oil in a large skillet over medium heat. Once hot, add the meatballs in batches, making sure not to overcrowd the pan.
Cook the meatballs for about 6-8 minutes, turning occasionally until they are golden brown on all sides and cooked through (internal temperature should be 165°F).
Once cooked, transfer the meatballs to a paper towel-lined plate to drain any excess oil.
Serve the meatballs hot, garnished with fresh parsley if desired.