Ingredients:

  • 1 lb (450 g) deli-sliced roast beef, shaved very thin
  • 4 onion buns, toasted
  • 1 tbsp (15 ml) olive oil
  • 1 cup (115 g) shredded sharp cheddar cheese
  • ½ cup (120 ml) low-sodium beef broth
  • 2 tbsp (30 g) unsalted butter
  • ¼ tsp (1.5 g) garlic powder
  • ¼ cup (60 ml) mayonnaise
  • 1 tbsp (15 ml) ketchup
  • 1 tsp (5 ml) apple cider vinegar
  • ½ tsp (2.5 g) smoked paprika
  • ⅛ tsp (0.5 g) cayenne pepper

Instructions:

  1. Whisk together the mayonnaise, ketchup, apple cider vinegar, smoked paprika, and cayenne pepper in a small bowl until smooth and uniform pale orange. Set aside.
  2. Melt the butter in a small saucepan over medium-low heat. Stir in the beef broth and garlic powder and bring to a gentle simmer. Gradually whisk in the shredded cheddar, stirring constantly until velvety and completely melted. Remove from heat immediately.
  3. Heat the olive oil in a non-stick skillet over medium heat. Add the shaved roast beef and toss gently for 2–3 minutes until heated through and just beginning to brown at the edges.
  4. Toast the onion buns in a toaster or oven until golden-brown and slightly crisp inside.
  5. Spread a generous layer of the red sauce on the bottom half of each toasted bun. Pile the warm roast beef high on the bun, pour the warm cheddar sauce over the meat until it cascades down the sides, close the sandwich, and serve immediately.