Special equipment: a disposable aluminum foil pan
Preheat a grill to medium-high heat and place a disposable aluminum foil pan on one side of the grill.
In a medium bowl, beat together the Cheddar, cream cheese, mayonnaise, garlic powder, smoked paprika and cumin until smooth. Set aside until needed or keep refrigerated in an airtight container for up 2 weeks.
Set aside 2 teaspoons of the chili seasoning. Sprinkle the steak with the remaining seasoning.
Add the butter, peppers and onion to the aluminum pan. Sprinkle with the reserved 2 teaspoons chili seasoning. Cook the vegetables, stirring occasionally, until tender, 2 to 3 minutes. Remove and let rest.
While the vegetables cook, drizzle the steak with oil and cook on the empty side of the grill until medium-rare to medium, about 5 minutes per side, depending on the thickness of the steak. Rest the steak on a rack for 5 minutes. Thinly slice against the grain and add to the pan with the vegetables. Lower the grill to medium heat.
Partially split the hoagie rolls, leaving just enough of the roll attached so they open like a book. Toast the cut side of the rolls on the grill. Spread a large spoonful of the cheese mixture onto each side of the rolls. Divide the steak, peppers and onions equally between the rolls. Top each with 2 slices of provolone. Close the sandwiches, wrap each in aluminum foil and put back on the grill to toast. Cook until the cheese is melted. Let cool slightly before unwrapping and serving.