Heat oil in large nonstick skillet, add onion and cook until golden and tender, about 10 minutes. Stir in 1 tablespoon seasoning blend, mix thoroughly and remove from heat.
Gently mix ground beef, 1 tablespoon seasoning blend, cilantro and egg whites or egg substitute. Mix well, and shape into 4 burgers. Preheat grill to medium-high heat and grill burgers for 8-10 minutes, turning once.
Toast buns and top with burger and spicy onions. Garnish with tomato and lettuce, if desired.