Instructions

• Slice your beef as thinly as possible. If you have a partially frozen steak (frozen for about 30 minutes), it's much easier to slice thinly with a sharp knife. In a large mixing bowl, combine soy sauce, gochugaru, brown sugar, sesame oil, minced garlic, fresh ginger, sriracha, rice vinegar, and black pepper. Whisk these together until well combined and the sugar has mostly dissolved. Add your sliced beef to the marinade and toss thoroughly, making sure every piece is coated. Cover and let marinate for at least 30 minutes at room temperature, or up to 4 hours in the refrigerator.
• Heat a large skillet over high heat until it's smoking hot. Divide your marinated beef into two batches. Add 1 tablespoon of oil to the skillet and allow it to heat for 30 seconds. Working with the first batch, spread the beef across the skillet in a single layer and let it cook undisturbed for 2-3 minutes to develop a nice crust. Stir and cook for another 2-3 minutes until the beef is caramelized and cooked through but still tender. Transfer to a clean plate and repeat with the second batch of beef, adding the remaining oil. Season with salt and pepper to taste.
• In the same skillet, add the red and orange bell pepper strips and onion slices. Cook over medium-high heat for 5-7 minutes, stirring occasionally, until the vegetables are tender and slightly charred. In the last minute of cooking, add the cooked beef back to the skillet along with the chopped scallions. Toss everything together for about 1 minute so the flavors meld.
• Split your hoagie rolls lengthwise without cutting all the way through. Toast them cut-side down in a dry skillet over medium heat for 2-3 minutes until they're golden brown and crispy. This prevents them from getting soggy when you assemble the sandwiches.
• Working quickly while everything is hot, divide the beef and vegetable mixture evenly among the four toasted rolls. Place 2 slices of provolone cheese on top of each sandwich. You can either let the residual heat melt the cheese, or place the sandwiches under a hot broiler for 1-2 minutes until the cheese is fully melted and gooey. Serve immediately.