2 large purple onions, sliced and chopped
2 Tbsp. olive oil
1 cup water
1/4 cup sugar
1/2 cup red wine vinegar
3/4 pound deli Italian roast beef
1 package King's Hawaiian butter rolls
1/2 pound sliced Swiss cheese
Preheat oven broiler. Heat olive oil in a large skillet over medium high heat. Add onions and sauté for 5 minutes. Add water, sugar and vinegar. Reduce heat to medium. Simmer another 15-20 minutes, stirring periodically, until onions are soft and jam is formed.
Place 2 slices of roast beef on each slider roll. Top with 1/4 slice Swiss cheese. Place sandwiches on a cookie sheet. Broil 1-2 minutes until cheese is melted. Remove from heat and add 1 Tbsp. onion jam and mustard to taste to each sandwich. Replace tops of rolls. Serve immediately.