Preheat the oven to 375°.
Add the stock, seasonings and roast beef to a slow cooker and cook on high heat for 1 hour. Keep warm.
Add the olive oil to a large saute pan on high heat and caramelize the peppers and onions. Once browned, keep warm.
Place the buns in an oven safe pan and evenly place the roast beef into the hoagie rolls. Top off with shredded cheese and roasted peppers and onions.
Cover with foil and bake for 20 to 25 minutes or until the cheese is melted.