Rum-Pepper Steak Sandwiches

(Courtesy of Cooking Light)

Ingredients:
Marinade
1/2 c. dark rum
2 Tbsp. brown sugar
1 Tbsp. coarsely ground black pepper
1/4 tsp. salt
5 garlic cloves, crushed, or 2 1/2 tsp. bottled minced garlic
1 (1 1/2 lb.) flank steak

Flavored Mayonnaise
1/2 c. fat-free or light mayonnaise
2 tsp. prepared horseradish

Remaining ingredients
8 (1/2 inch thick) slices red onion (about 2 onions)
16 (1 oz.) slices sourdough bread
2 c. thinly sliced romaine lettuce
16 (1/4 inch thick) slices tomato (about 3 tomatoes)

Directions:
To prepare marinade, combine first 5 ingredients in a large ziploc bag.  Trim fat from steak then add the steak to the bag.  Seal and marinate in refrigerator for at least 2 hours, turning bag occasionally.  Remove the steak from the bag, reserving marinade.  Pour the marinade into a microwave-safe dish.  Microwave on on for 1 minute or until mixture boils.

To prepared flavored mayonnaise, combine mayonnaise and horseradish in a small bowl.  Set aside.

Prepare grill.

Place steak and red onion slices on a grill rack, and grill onions 4 minutes on each side, basting with the reserved marinade.  Remove onions from the grill.  Turn steak, and grill an additional 8 minutes or until steak is desired degree of doneness.  Remove steak from grill.  Place bread slices on grill rack then grill for 2 minutes on each side or until toasted.

Cut steak diagonally across the grain into thin slices.  Spread 1 Tbsp. flavored mayonnaise on one side of each of the 8 toasted bread slices.  Divide steak, onion slices, lettuce and tomato slices evenly among 8 bread slices.  Top with remaining bread slices.  

Note~  Can substitute pineapple juice for the rum if desired.