4 sub rolls (6 inches sliced lengthwise with one side intact)
8 slices American cheese
Directions for Sauce
Mix all ingredients together in a small saucepan over medium-high heat. Bring mixture to a boil, reduce to simmer, and cook stirring constantly until slightly thickened; set aside.
Directions for sandwiches
Preheat oven to 350F – oven rack in the middle position.
Using the oil in a large nonstick skillet over medium-high heat cook the onion and burger seasoned with the salt and pepper until liquid has evaporated and burger starts to sizzle (break burger up with a spoon as it’s cooking.) Add one cup of the prepared sauce, bring mixture to a boil, reduce heat to medium, and simmer until slightly thickened about 1 minute.
Place rolls on a baking sheet and divides the meat mixture evenly over the bottom of the rolls. Top each sandwich with 2 slices of cheese. Bake until cheese has melted and sandwiches are heated through (about 5 minutes). Spread any remaining sauce over the top of each sandwich, fold, and serve hot.