Before making the recipe put the meat in the freezer for 20-30 minutes then slice. The colder meat will slice easier.
In a large skillet add olive oil over medium low heat. Then add onion and bell peppers when oil is hot. Cook, stirring occasionally, until very tender. If your vegetables start to brown, turn the skillet down a little.
While vegetables are cooking, slice meat thinly by removing it from the refrigerator, placing it on a cutting board and using a sharp knife to trim off excess fat and slice as thinly as possible against the grain. Then chop the steak into very small pieces, about ¼’’ pieces.
When the vegetables are tender, transfer to a dish and return the skillet to heat. Add the tablespoon of olive oil to the skillet and turn heat to medium-high. Add steak and cook, stirring frequently for about 4-5 minutes. Season with salt and pepper while cooking. Remove meat from pan with a slotted spoon and add to vegetable mixture.
Turn on the oven to high broil.
Split open the hoagies, but do not separate them. Spread them with softened butter on each side inside the bun. Place on a baking pan and transfer to the oven with the oven rack being on the highest slot. Broil for 1-2 minutes keeping a close eye on them as they will burn quickly. Remove from the oven.
Drain off all juices from the skillet that the meat was cooked in. Add the steak and vegetables back into the pan. Place the provolone slices over the top of the mixture and cover the pan. Cook on medium until the cheese melts about 4-5 minutes. Stir and then transfer to prepared hoagies buns with tongs.