Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper or lightly grease a baking dish.
In a large mixing bowl, combine the ground turkey, breadcrumbs, chopped onion, feta, garlic, egg, oregano, dill, cumin, salt, and pepper.
Mix gently until just combined, avoiding overmixing.
Roll the mixture into 1-inch meatballs and arrange them on the prepared baking sheet.
Bake the Greek Turkey Meatballs with Tzatziki Sauce for 15–20 minutes, or until the meatballs reach an internal temperature of 165°F (74°C).
For extra color, you may brown the meatballs in a skillet for 2–3 minutes before baking.
Serve immediately with chilled tzatziki sauce and fresh lemon wedges.