London Broil Steak Sandwiches with Cheese sauce

I know I've posted a steak and cheese sandwich recipe on here before, but I tried another version with London broil steak that I marinated for 24 hours. Then I had to try it with my homemade cheese sauce! Oh man these were good, but way messy! That makes them all the better right?

London Broil Steak Sandwiches

1- 2 to 3 pound London broil steak
1/4 cup olive oil
1/4 cup red wine vinegar
1 Tablespoon Grill Mates SPICY Montreal Steak Seasoning
Whisk oil, vinegar, and steak seasoning together. Put steak in ziploc bag and pour marinade over it. Close bag and mush around a bit, then let marinade over night in the refrigerator.

When you're ready to make the sandwiches you'll need:
1/2 onion, sliced thinly
1/2 green bell pepper, sliced thinly
1/2 red bell peper, sliced thinly
Cheese sauce, warmed (see my recipe for mac and cheese, I used that cheese sauce)
Sandwich rolls

Heat grill to med/medium high heat. I heat my veggie grill tray too. When hot put veggies on grill tray, and steak on grill. Cook veggies about 10 minutes turning every so often so they don't burn. Cook steak about 6 minutes per side, or till desired doneness. We like ours medium rare so there is a little pink in the middle.
When steak is done, remove to a plate and let rest 5 to 10 minutes. Remove vegies when they are crunchy tender to a plate. Grill sandwich rolls opened up, for a minute on each side so you get nice grill marks, and they are slightly crisped.
Slice steak in very thin slices against the grain. London Broil is a tougher piece of steak so the thinner the slice the better and against the grain makes it easier to bite into.
To assemble sandwiches, place slices of steak on bottom of sandwich roll, then add peppers and onions, and top with a good helping of cheese sauce and top of sandwich roll. Have lots of napkins ready, and dig in!! I served with chips and guacamole. Yummo!!