1. I always start with the cheese sauce. To begin, shred the provolone.
2. Next, a small sauce pan, melt the butter over medium heat.
3. When the butter is melted, add the flour and whisk until it is completely combine. I usually whisk it a minute or two after it has finished combining to let the flour cook a little more. It, in my mind, gives it a little more flavor.
4. Now, add in the milk. Don't dump it in all at once! Stir it in slowly, pouring a little bit in at a time or you run the risk of lumps.
5. Now add the cheese, a bit of salt, and garlic powder.
6. Once it has all melted, and is combined into a creamy sauce, keep it warm on another eye (set to it's lowest setting) to use later.
7. Turn your oven to broil. Open the hoagie rolls so that the interior is exposed and place them on a baking sheet. Since we're broiling here, you'll want to keep an eye on them. For my over it takes 5-6 minutes for the over to heat up and start to toast the bread. Your oven may be different (and probably is) so keep an eye on it. Once it gets hot they'll burn in no time. Once they're toasted set them aside for alter.
8. For the sandwich, remove the steak(s) from the fridge^{(see note 1)} and slice it as thinly as you possibly can. This works better while the steak is really cold. You can even put it in the freezer for a little while if you like, but I find straight from the fridge is usually cold enough.
9. Remove the seeds and ribs from the bell peppers and slice them into thin strips. For just two sandwiches you'll only need half of each pepper.
10. Cut the red onion in half, length wise (from the top through the "hairy" bottom) and then slice it as thinly as possible.
11. Head some oil in a medium cast iron skillet over medium-high heat.
12. Once the oil is hot add the steak and sauté it until it is warmed all the way through. Don't worry that it is cooked all the way through. I like my steaks medium rare, but for this sandwich I like it well. It just tastes better.
13. When the steak is cooked through, remove the steak and add the bell peppers and onions and stir them until they start to soften ^{(seen note2)}. It's okay if they start to brown a little. It only adds to the flavor.
14. Add the steak back into the pan and sprinkle some salt, pepper, and granulated garlic over everything and give it a stir. Mix everything well and let the steak warm back up and the flavors to mix a bit.
15. Now it's time to make a sandwich! Open the rolls and pile each one high with the steak, pepper, and onion mixture. Next poor the cheese sauce over each one (as much or as little as you like, you should have plenty) and enjoy!

Cook's Notes:

¹ I use leftover steak. When I grill (or pan sear them in cast iron on the stove) steaks there's always too much for both of us. This is one of my favorite ways to use up the leftovers. You could start by grilling the steaks, but why do that just for the sandwich when you can have the steaks and the sandwich too!

² You could, in theory, cook everything all at once. I tend to over cook the steak when I do it that way.