If using pre-cooked brisket or tri-tip, warm slices gently: place sliced beef in an oven-safe dish, sprinkle with kosher salt and pepper, cover with foil and warm in a 325°F (160°C) oven for 10–15 minutes until heated through. If using chilled cooked beef, separate slices so they reheat evenly.

Toast hoagie rolls

Split hoagie rolls lengthwise, spread about 1/2 tablespoon softened butter on each cut side. Place cut-side up on a baking sheet and toast in a 375°F (190°C) oven for 5–7 minutes, or until edges are golden and slightly crisp. Alternatively, toast under a broiler briefly, watching closely to avoid burning.

Assemble sandwiches

Spread about 1/2 tablespoon yellow mustard on the bottom half of each toasted roll. Divide the warmed beef evenly among the 4 rolls, piling it so each sandwich gets roughly 4 ounces. Top the beef with 2 slices (about 1–2 oz) of Havarti cheese per sandwich and, if using, scatter about 1 tablespoon pickled banana peppers per sandwich. Close sandwiches. If you prefer the cheese melted, return assembled open sandwiches (cheese on top) to the 375°F oven or under a broiler for 1–2 minutes until cheese is melted and bubbly.

Final seasoning and serve

If desired, brush the outside of each toasted roll lightly with the remaining softened butter. Slice each hoagie in half on the diagonal. Serve each sandwich immediately with a small bowl of au jus for dipping.

Au Jus

Start the base: In a medium saucepan over medium heat, add 1 tablespoon neutral oil (or use a small amount of the beef drippings if available). Add the finely minced shallot and minced garlic and sauté 1–2 minutes until softened and fragrant but not browned.

Deglaze and reduce: Add the dry red wine to the pan to deglaze, scraping any browned bits off the bottom. Let the wine reduce by about half, 2–3 minutes.

Add liquids and flavorings: Pour in the beef stock and the 1/4 cup beef drippings or au jus concentrate. Stir in the Worcestershire sauce and add the thyme sprigs. Bring the mixture to a gentle simmer and reduce heat to low. Simmer uncovered 8–10 minutes to concentrate flavors.

Finish and season: Remove thyme sprigs. Taste and adjust seasoning with salt and freshly ground black pepper. For a slightly richer finish, whisk in 1 tablespoon cold unsalted butter until melted. If you prefer a slightly thicker jus, make a slurry by mixing 1 teaspoon cornstarch with 1 teaspoon cold water, then whisk it into the simmering jus and simmer 1 minute more until slightly thickened. Keep warm until ready to serve.

Strain (optional): For a smooth au jus, strain the sauce through a fine-mesh sieve into a serving bowl or gravy boat, pressing gently on solids to extract flavor.