Sear the beef

• Heat the oil in a frying pan over medium-high heat.
• Add the ground beef and chopped onion, then season with salt, black pepper and garlic powder.
• Let the beef brown without stirring for a few minutes to develop a crust.

Chop and melt the cheese

• Chop and break up the beef with a spatula, mixing it with the onion.
• Lay the American cheese slices over the meat and let them melt.
• Chop everything together until the cheese is fully incorporated.

Toast the rolls

• Split the hoagie rolls and toast them cut-side down in the pan or in a hot oven until golden.

Assemble and serve

• Spread mayonnaise and ketchup inside the toasted rolls.
• Fill with the chopped cheese mixture.
• Top with shredded lettuce and sliced tomato and serve immediately.