To prepare marmalade, heat butter and olive oil in large nonstick skillet over medium heat until hot. Add onions; cook 8 to 10 minutes or until tender and beginning to brown, stirring occasionally. Stir in wine, prunes, preserves and vinegar. Cook 5 minutes or until liquid evaporates and marmalade thickens and turns dark, stirring occasionally. Remove from heat; stir in thyme and salt. Set aside to cool.
Rub both sides of beef steak with garlic; sprinkle evenly with pepper. Place steak on grid over medium, ash-covered coals. Grill, covered, 7 to 11 minutes (over medium heat on preheated gas grill, 8 to 13 minutes) for medium rare (145°F) to medium (160°F) doneness, turning occasionally. About 2 minutes before steaks are done, place rolls, cut sides down, on grid. Grill until toasted.
Carve steak into thin slices. Evenly layer steak slices, marmalade and cheese on bottom of each roll. Close sandwiches; cut each crosswise in half.
Recipe and photo as seen in The Healthy Beef Cookbook, published by Houghton Mifflin Harcourt
Nutrition information per serving: 509 Calories; 117 kcal Calories from fat; 13 g Total Fat; 5 g Saturated Fat; 6 g Monounsaturated Fat; 6 mg Cholesterol; 555 mg Sodium; 59 g Total Carbohydrate; 3.4 g Dietary Fiber; 33 g Protein; 4.5 mg Iron; 10.3 mg Niacin; 0.7 mg Vitamin B6; 1.4 mcg Vitamin B12; 5.2 mg Zinc; 32.7 mcg Selenium;