In a large bowl, combine the ground turkey, chopped onion, minced garlic, parsley, oregano, cumin, salt, and pepper. Mix everything together until it’s well combined.
Form the mixture into small meatballs, about 1 inch in diameter.
Heat olive oil in a large skillet over medium heat. Once hot, add the meatballs and cook, turning occasionally, until they’re browned and cooked through, about 10-12 minutes.
While the meatballs are cooking, prepare the quinoa or brown rice and chop the vegetables.
To assemble, divide the quinoa or rice among bowls. Top it with the cooked meatballs, cherry tomatoes, cucumber, olives, red onion, and crumbled feta cheese.
Drizzle the tzatziki sauce over the top and garnish with fresh lemon wedges. Serve immediately.