Freeze thawed steak for 10 minutes to make steak easier to cut. After slice against the grain into 1/4 inch wide strips
In a large skillet, heat 1 tbsp of oil over high heat. Add half the steak and season with 1/2 tsp of fajita seasoning. Stir occasionally until browned. I found it took about 5-6 minutes total. Transfer to a plate and cover with foil (I place in microwave to help keep warm). Repeat the process for the second half of the uncooked steak. Once cooked place with your other cooked steak to keep warm.
Reduce the heat of the skillet to medium/medium-high and add butter and remaining tablespoon of olive oil. Heat until the butter starts to bubble. Add onion, salt and black pepper and cook until onion is softened and translucent. This takes about 6-7 minutes.
Add bell peppers, poblano peppers and 1 tsp of fajita seasoning and saute. Stir often until peppers and onions are carmaelized. I found this takes at minimum 20 minutes if not a bit longer.
Turn your broiler on high and have a rack a few inches from the heat. Prep a baking sheet with foil.
Add steak to the skillet and toss to combine. Heat through for about 5 minutes and then remove from heat.
Open rolls and set on the baking pan. Divide the steak and pepper mixture amont the rolls and cover with slices of cheese. These are open faced sandwiches so the cheese can melt appropriately.
Broil until cheese begins to bubble, about 3-4 minutes. Watch carefully so they don't burn. Serve immediately and enjoy!