Fry onion rings and optional bell pepper in butter until tender and slightly browned.
Remove vegetables from the pan; keep warm.
Add meat to the pan and heat throughly. (If there are any browned spots from the meat and vegetables left in the pan, you can deglaze the pan with a little bit of red wine and then add it to the broth for a tasty addition).
Layer one slice of cheese, meat, veggies and another slice of cheese on French bread rolls.
Cover with other half of roll.
Place sandwiches back in pan over low heat, covered.
Heat just until cheese is melted and bottom of rolls are toasted.