Fire up your Pit Boss KC Combo and preheat griddle to 375° F. If using a gas or charcoal grill, set heat to medium heat. For all other grills, preheat cast iron skillet on grill grates.
Melt 1 tablespoon of butter and 1 tablespoon of olive oil on griddle. With a serrated knife, slice rolls 3/4 of the way through, then place facedown onto griddle and cook until toasted. Set aside.
Melt remaining tablespoon of butter and olive oil on the griddle. Add sliced onions and cook for 2 minutes, or until lightly caramelized. Move to the lower-right corner of griddle to keep warm.
Season steak generously with Pit Boss Chop House Steak Rub, then place on griddle and cook for 3 minutes, stirring to brown all sides. Mix in caramelized onions.
Divide steak and onions into 4 portions on the griddle, then top each with 2 slices of provolone cheese. Let cheese melt slightly and transfer to a toasted hoagie roll using a bench scraper or metal spatula. Serve hot and enjoy!