In a large mixing bowl, add in ground turkey/chicken, red onion, egg, bread crumbs, garlic cloves, salt, pepper, cumin, oregano, and lemon zest. Mix well until combined. Roll out 1 inch meatballs.
Heat a cast iron skillet over medium heat, add the oil, and heat for 1-2 minutes. Add the meatballs, with space in between, and cook for 8-10 minutes, or until golden brown and cooked through.
In a small bowl, mix together Greek yogurt, lemon juice, fresh dill, cucumber, salt, and pepper. Taste test for seasonings, add more salt and pepper if needed, cover, and refrigerate until bowls are ready to assemble.
Assemble each bowl with a bed of greens and a small scoop of cooked quinoa. Top with cooked Greek meatballs, Tzatziki, pickled red onions, cherry tomatoes, cucumbers, and Feta cubes.