Preheat the oven to 400°F (204°C) with the center rack in place.

Season the sliced ribeye with kosher salt and sear it in a hot cast iron skillet with vegetable oil for about 4 minutes per batch; then set aside.

Sauté chopped onions in the same skillet over medium heat until golden and tender, around 5-8 minutes.

Mix together mayonnaise and grated garlic to prepare the garlic mayo. Spread it generously on the buttered sides of your hoagie rolls.

Toast the hoagie rolls in the oven until golden, about 4 minutes.

Return the beef to the skillet with the onions, then season with freshly cracked black pepper and stir until warmed through.

Top the beef mixture with provolone slices, allowing the cheese to melt.

Assemble sandwiches by filling the hoagie rolls with the warm beef and melted cheese mixture. Serve immediately.