This is our favourite sandwich to have for dinner on a lazy weekend. I like to serve it with sweet potato fries and a Caesar salad. Mmm . . . mmm . . . scrumptious!
Season steaks with salt and pepper; allow steaks to come to room temperature, about 15 minutes.
Heat oil in a skillet over medium heat until very hot; lay steaks in pan and cook until they are beginning to firm and are hot and slightly pink in the center, about 5 minutes per side. An instant-read thermometer inserted into the center should read 140 degrees F (60 degrees C). Transfer steaks to a warm plate; cover and let rest, about 10 minutes.
Melt butter in same pan over medium heat; stir in mushrooms and peppers. Season with salt and pepper; cook and stir until tender, about 5 minutes.
Set oven rack about 6 inches from the heat source and preheat the oven’s broiler.
Toast buns under the broiler until golden, about 2 minutes. Divide mozzarella cheese over bottom halves of buns; return to broiler until cheese melts, about 2 minutes.
Slice steak very thinly. Pile steak slices over cheese-topped bun halves; top with mushrooms and peppers. Spread mayonnaise on top halves of buns; place over sandwich.
Per Serving: 1132 calories; protein 48.5g; carbohydrates 74.9g; fat 70.5g; cholesterol 130.2mg; sodium 1304.7mg.