Take the first six ingredients and combine in a marinade dish. Let marinade overnight.

Heat a skillet or enamel pot on medium high heat. Add the oil and let get good and hot.

Sear the steak on both sides for 3 - 4 minutes.

Put in a 300 degree oven for 4 plus hours. Remove from oven and set aside.

Meanwhile, heat a skillet on medium high heat. Add the oil and butter and warm.

Drop in the onions. Stir frequently and cook for 25 - 30 minutes.

Once the onions are caramelized, remove from heat and set aside.

Assemble sandwich by slicing the roll open. Place a couple of slices of the cheese on the roll.

Add a decent size of flank steak and top with a good amount of the onions.

Place in a 275 degree oven and cook for 5 minutes or so. You just want a good melt on the cheese.

Serve and enjoy!