Steak Sauce Burgers

 

2 T. butter

1 onion, thinly sliced

¾ lb. ground beef

¼ cup steak sauce, divided

1 slice Swiss cheese

¼ cup mayonnaise

1 T. prepared horseradish

1 T. chopped fresh parsley

2 French steak rolls, split and toasted

 

Preheat grill or grill pan to medium-high heat. Melt butter in a skillet over medium-high heat. Add onion; cook 15 minutes, stirring often, until onion is very tender and browned. Stir in 2 T. steak sauce. Meanwhile, combine beef and 2 T. steak sauce. Shape mixture into 2 oblong patties to match the shape of the rolls. Season lightly with salt and pepper. Grill patties, covered, 5 to 6 minutes per side or until no longer pink. Top each with 1 slice cheese, and grill 1 minute longer or until cheese is melted. Stir together mayonnaise, horseradish, and parsley in a bowl. Serve cheese-topped patties on toasted rolls with saucy onions and mayonnaise mixture.