Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper if desired.
In a large mixing bowl, combine the ground turkey, breadcrumbs, Parmesan cheese, parsley, egg, garlic, oregano, salt, black pepper, and onion powder. Mix until well combined.
Roll the mixture into meatballs, about 1.5 inches in diameter, and place them onto the prepared baking sheet.
Drizzle the meatballs with olive oil to help them brown while baking.
Bake in the preheated oven for about 20 minutes or until the meatballs are cooked through and browned on the outside.
While the meatballs are baking, prepare the tzatziki sauce. In a separate bowl, mix the Greek yogurt, grated cucumber, olive oil, lemon juice, garlic, dill, and salt. Stir until well combined and refrigerate until serving.
Once the meatballs are cooked, serve them warm alongside the tzatziki sauce for dipping.