Combine the salt, pepper, paprika, and garlic together in a small bowl for the seasoning.
Cut beef into thin strips. Cut the mushrooms, onion and peppers into thin strips.
In a skillet, heat 1 tsp oil with 1 Tbsp butter. Add the beef, saute until almost fully cooked. Season with half of the prepared seasoning. Remove from skillet and cover to keep warm.
Add remaining 1 tsp oil and 1 Tbsp butter. Add the peppers, mushrooms and onions. Cook over medium heat until vegetables are tender. Add the steak back into the skillet, season with remaining seasoning and toss to combine.
Cut the rolls in half removing the tops. Add the bottom of buns to a casserole dish. Remove the tops of the buns. Spread mayo over bottom of buns.
Add the cooked beef and vegetables and spread evenly. Top with the cheese.
Close buns.Prepare butter spread. Combine melted butter, Italian seasoning, and garlic powder and mix. Generously brush the tops of rolls.
Cover dish with foil and bake for 15 minutes at 375°F, remove and bake another 5 minutes or until cheese completely melts.