In a large bowl, combine the ground turkey, grated apple, chopped sage, onion powder, breadcrumbs, egg, garlic, salt, and pepper.
Mix until just combined, being careful not to overmix.
Shape the mixture into evenly sized meatballs.
Heat the olive oil in a skillet over medium heat.
Brown the meatballs on all sides, then reduce the heat and cook through, until they reach an internal temperature of 165°F (74°C).
Serve with your choice of sauce, pasta, or mashed potatoes.