Heat oil in a large skillet over medium-high heat; add onion and cook 5 minutes or until golden brown, stirring often. Stir in 1 tablespoon TABASCO® Chipotle Sauce and the Worcestershire sauce; mix well and remove from heat.
Combine ground beef, cilantro, green onion, salt and the remaining 3 tablespoons TABASCO® Chipotle Sauce; mix well and shape into 4 burgers. Grill over medium-high heat to desired doneness, about 3 minutes per side for medium-rare. Top each burger with a slice of cheese and grill just until melted. Place on buns and top with spicy onions and baby greens.
Makes 4 servings.