1 medium yellow onion, cut into 1/4-inch-thick slices
4 slices Swiss cheese
4 hamburger buns
In 12-inch nonstick skillet, melt 2 tablespoons Country Crock® Spread over medium-high heat and cook mushrooms and onion, stirring frequently, 2 minutes. Reduce heat to medium and cook, stirring occasionally, 4 minutes or until vegetables are tender and golden. Season, if desired, with salt and ground black pepper. Remove vegetables and keep warm.
Shape steak into 4 patties. Season, if desired, with salt and ground black pepper. Grill or broil until desired doneness.
Meanwhile, melt remaining 2 tablespoons Spread and brush on buns. Grill 1 minute or until toasted. Serve burgers on toasted buns, topped with cheese and mushroom mixture.