Heat the olive oil in a large skillet over medium-high heat. Add the sliced green pepper, red pepper, and onion. Sauté for 3 to 4 minutes until softened. Add the shaved ribeye steak to the skillet and cook, stirring, until no pink remains. Sprinkle with seasoned salt and, if using, drizzle with Cheez Whiz. Stir well to combine, then remove from heat and keep warm.

Spread a thin layer of mayonnaise or softened butter on one side of each slice of bread. Heat a clean skillet or griddle over medium heat. Place half of the bread slices on the skillet, mayo-side down. Layer each with a slice of provolone cheese, a generous scoop of the steak and pepper mixture, and then another slice of provolone. Top with the remaining bread slices, mayo-side out. Grill until golden and crisp, about 2 to 3 minutes per side, flipping carefully to ensure the cheese fully melts and the bread is evenly toasted.

Cut the sandwiches in half and serve hot.