Preheat the oven to 400 degrees F or heat 2 inches of vegetable oil in a heavy-bottomed pot, or in a countertop fryer. Bake or fry the French fries and mozzarella sticks according to the package directions.
Meanwhile, heat 1 tablespoon of the olive oil in a large nonstick skillet over medium-high heat. Add the garlic, onions, 1/4 teaspoon of the salt and some pepper. Cook, stirring, until the onions are tender and lightly browned, 3 to 4 minutes. Scrape into a bowl and set the skillet back over medium-high heat.
Heat the remaining 1 tablespoon olive oil until just beginning to smoke. Scatter the beef in the skillet and sprinkle with the remaining 1/2 teaspoon salt and some pepper. Let the beef cook undisturbed for 2 minutes, and then quickly stir once or twice, breaking some of the clumps of beef apart. Continue to cook until the beef is just cooked through and browned, another 2 to 3 minutes, stirring once or twice more if needed. Remove from the heat and add the beef to the bowl of onions. Stir to combine.
Put 4 slices of the cheese on the bottom half of each loaf of bread. Evenly top with the steak and onions. Add a handful of fries and 4 mozzarella sticks in each sandwich.
Bake the assembled hoagies (don't close them up yet) until the cheese is melted, 6 to 8 minutes. Top with ketchup and/or hot sauce. Cut each hoagie into 3 to 4 pieces. Serve warm.