Preparation Melt 1 tablespoon butter in heavy large skillet over medium-high heat. Sprinkle steak with salt and pepper. Add steak to skillet and sauté to desired doneness, about 4 minutes per side for medium-rare. Transfer steak to cutting board. Melt remaining 3 tablespoons butter in same skillet over medium-high heat. Add onion and garlic; sauté until tender, about 8 minutes. Add chili sauce, Worcestershire sauce, lemon juice and brown sugar. Simmer 3 minutes to blend flavors, stirring occasionally. Season sauce to taste with salt and pepper. Slice steak thinly. Arrange on platter. Spoon some sauce over. Serve, passing remaining sauce separately.
Preparation Melt 1 tablespoon butter in heavy large skillet over medium-high heat. Sprinkle steak with salt and pepper. Add steak to skillet and sauté to desired doneness, about 4 minutes per side for medium-rare. Transfer steak to cutting board. Melt remaining 3 tablespoons butter in same skillet over medium-high heat. Add onion and garlic; sauté until tender, about 8 minutes. Add chili sauce, Worcestershire sauce, lemon juice and brown sugar. Simmer 3 minutes to blend flavors, stirring occasionally. Season sauce to taste with salt and pepper. Slice steak thinly. Arrange on platter. Spoon some sauce over. Serve, passing remaining sauce separately.