Preheat the oven to 200 degrees F.
Heat a cast-iron skillet or griddle over medium-high heat. When hot add the oil, onions and bell peppers, and cook, stirring, until caramelized, about 6 minutes. Add the garlic, salt, and pepper, and cook, stirring, for 30 seconds. Push off to 1 side of the griddle.
Add the meat to the hot pan and cook, stirring and breaking up with the back of 2 metal spatulas, until almost no longer pink, about 2 minutes. Mix in the sauteed vegetables. Top with cheese slices and melt. Spoon the cheesy meat mixture into the warm buns and serve immediately with condiments of choice or Put the meat in the bun and dip the spatula in the cheese whiz and then wipe the spatula down the inside of the bread.
Yield: 2 sandwiches