In a large bowl combine the spinach, red onion, feta, dill, oregano, garlic, salt and pepper, and the ground turkey.
Use your hands to mix everything together, but don't overwork.
Form the meat mixture into 4 patties.
Heat your grill, grill pan, or skillet over medium heat. Spray or coat the grill grates/pan with oil.
Grill the burgers for approximately 4-6 minutes then flip over and grill another 4-6 minutes or until done.
Serve the turkey burgers in pitas topped with the tzatziki sauce, Greek tomato salad and more crumbled feta.