Sensational Steak Sandwich

Step 1
Heat oil in a large skillet over medium heat. Add steak and cook until browned. Add mushrooms, bell pepper, and onion; cook and stir until just tender, about 5 minutes.

Step 2
In a slow cooker, combine beef broth, salt, pepper, Worcestershire sauce, red pepper flakes, and red wine. Transfer steak and vegetables to the slow cooker; stir to blend. Cover and cook on High for 3 to 4 hours, or until beef is extremely tender.

Step 3
Preheat the oven to 425 degrees F (220 degrees C). Drain liquid from the slow cooker and save for dipping.

Step 4
Slice French bread loaf lengthwise like a submarine sandwich. Mix together horseradish and mustard; spread onto the inside of loaf. Place slices of provolone cheese on both sides of loaf, then fill with steak and vegetables. Close the loaf and wrap with aluminum foil.

Step 5
Bake for 10 to 15 minutes in the preheated oven. For crunchier bread, you can bake it without the aluminum foil. Slice into 4 sandwiches; serve with the juices from the slow cooker for dipping.