In a large bowl, mix the ground turkey, breadcrumbs, egg, minced garlic, chopped onion, parsley, oregano, cumin, salt, and black pepper. Combine until just mixed.
Shape the mixture into small meatballs, about 1 to 1.5 inches in diameter.
If pan-frying, heat olive oil in a skillet over medium heat and cook the meatballs for about 3-4 minutes per side, until browned and cooked through. If baking, place the meatballs on a lined baking sheet and bake at 400°F (200°C) for 18-20 minutes, flipping halfway.
While the meatballs cook, prepare the tzatziki sauce by combining Greek yogurt, grated and drained cucumber, minced garlic, lemon juice, chopped dill, olive oil, salt, and pepper in a bowl. Stir well and refrigerate for 10 minutes before serving.
Serve the meatballs warm with tzatziki sauce and enjoy!