Mix turkey, corn meal, egg substitute, seasoned salt and chili powder in a medium bowl. Divide mixture evenly into 8 patties. Top four patties with a slice of cheese and cover with remaining 4 patties. Press edges together to seal in cheese. Grill burgers over medium-hot coals for about 5 minutes on each side. Mix yogurt and salsa together in a small bowl. Place a burger on each bun and top with onion, arugula and salsa mixture.