Preheat the oven:
Set your oven to 425°F (220°C).

Cook the steak:
Heat an oven-safe skillet over medium-high heat and add 1 tablespoon of olive oil. Thinly slice the steak, season with garlic salt and black pepper, and cook until browned. Remove the steak from the skillet and set aside.

Sauté the vegetables:
Reserve 1 tablespoon of the cooking liquid from the skillet and discard the rest. Return the skillet to the heat, add the green pepper and onion, and cook in the reserved liquid until tender but still slightly crisp. Remove the vegetables and set aside.

Layer fries and toppings:
Spread a layer of fries in the skillet (or a baking dish). Place 4 slices of white American cheese on top of the fries. Add a layer of cooked steak and sautéed vegetables. Repeat the layers, ending with the remaining cheese slices on top.

Bake:
Place the skillet in the preheated oven and bake for 8-10 minutes, or until the cheese is melted and bubbly.

Serve:
Remove from the oven, let cool slightly, and serve hot.