I got this recipe from my mother-in-law, it can be a messy sandwich to eat, but is worth it.
1 lbs. sliced pastrami
½ lbs. deli roast beef
¼ lbs. baby Swiss cheese, thinly sliced
1 large purple onion, sliced
¾ c. red wine vinegar
1 ½ c. sugar
1 green bell pepper, sliced into rings
1 loaf French bread (or you can use 6 single serving hoagie type rolls)
3 Tbsp. mayonnaise
2 Tbsp. mustard
1. Place the onion and bell pepper into a medium bowl. Mix with the vinegar and half of the sugar. When it starts to thicken add the rest of the sugar. Let stand in refrigerator until caramelized.
2. Slice the bread in half lengthwise, on one half of the bread butter and sprinkle with parmesan cheese.
3. Heat the meat in the microwave and place on the opposite half of the bread. Top with Swiss cheese and onions/peppers. Broil both halves until cheese melts and butter side is toasted. Spread with mayonnaise and mustard. Put the halves together and slice to serve.