Roast Beef Sandwich Recipe

Prep and soak

Peel (optional) and cut russet potatoes into 1/4–1/2-inch fries. Place cut fries in cold water and soak 20–30 minutes to remove excess starch. Drain and pat completely dry with kitchen towels.

Optional dusting

If using cornstarch: toss dried fries with 1 tablespoon cornstarch to lightly coat, then shake off excess.

Fry

Heat 2 cups vegetable oil in a heavy pot or deep fryer to 325°F (use medium heat). Fry potatoes in batches for 3–4 minutes until just softened and pale gold. Remove to a wire rack. Increase oil to 375°F and fry a second time for 2–3 minutes until golden and crisp. Drain on paper towels and season with 1 tsp salt and 1/4 tsp black pepper while hot.

Warm beef

If roast beef is leftover cold slices, place them in a shallow saucepan with 1/2 cup of the au jus over low heat. Add 1 tablespoon olive oil, 1/2 tsp salt and 1/4 tsp pepper. Warm gently, stirring occasionally, until heated through (about 3–5 minutes). If using deli-style roast beef, warm similarly for 1–2 minutes to avoid drying.

Prepare au jus (if using pan drippings)

If making au jus from pan drippings: scrape pan drippings into a small saucepan, add 1 cup beef stock, 1/2 cup red wine (optional), simmer briefly and skim fat. Reduce to about 1 cup total and strain. Season to taste. If using store-bought, warm gently until hot and keep at a low simmer.

Prepare rolls

Split hoagie rolls lengthwise without separating completely. Butter cut sides with the 2 tablespoons unsalted butter and sprinkle the buttered sides with 1/2 tsp garlic powder if using.

Toast rolls

Heat a skillet or griddle over medium heat. Place buttered roll halves cut-side down and toast 1–2 minutes until lightly golden and crisp.

Assemble sandwiches

Spread 1/2 teaspoon Dijon mustard on the bottom half of each roll. Pile approximately 4 ounces (about 1/4 lb) warmed roast beef onto each roll. Drizzle or ladle about 2 tablespoons of the warm au jus over the meat per sandwich (reserve extra for dipping). Top each sandwich with 1 slice provolone cheese. If you prefer melted cheese, place assembled sandwiches under a broiler or in the skillet covered for 30–60 seconds until cheese is melted.

Finish and serve

Close sandwiches and cut each in half if desired. Transfer fries to the plate alongside sandwiches. Pour remaining warmed au jus into small individual dipping bowls. Garnish fries with chopped parsley if using. Serve immediately.

For best texture, fry potatoes just before serving so they stay crisp. Adjust au jus seasoning with salt and pepper to taste. If you want a cheesier sandwich, add a second slice of provolone or swap for Swiss or mozzarella.