Note: you can use leftover steak and skip the cooking steak instructions.
To prepare the steak:
Combine all the ingredients for the marinade in a large zip-top bag, mix it and add the steak.
Close it tight and place it in a wide bowl to refrigerate for about 4 hours.
Prepare the grill to a two-temperature zone and make sure the hot zone is set to hot temperature, about 425°-450°.
Take the steaks out of the marinade and let excess marinade drip off back into the back. Place them over direct heat and sear for about 4 minutes on each side.
After you get a nice sear on each side, move steaks to the cool side of the grill and let them cook until it reaches your desired temperature. (It’s best to cook tougher steaks is no more than medium.)
Take off heat and let the steak rest for 5-10 minutes and slice it thin against the grain.
To make the sandwiches:
Note: You will need to prepare the grill for two temperature zones if you didn't cook the steak first.
Spread butter on the outside of each bread slice and place it on a flat grill basket, butter side down.
Slice cheese and spread it evenly over each slice of bread.
Spread slices of steak on two of the bread slices.
Place the grill basket with sandwich halves on the grill, on the cooler side of the grill, not over direct fire. Cover with a lid and let it cook until the cheese starts to melt.
Cover the slice of bread with the steak on it with the other slice without the steak and gently press. Continue to cook until the outside is golden brown and all the cheese is melted.
Take off the grill and let the sandwiches cool down for a few minutes before cutting.