Corned beef burger

Ingredients:

Caramelized onions

• 2 tablespoons unsalted butter
• 2 medium yellow onions, thinly sliced ​​(about 4 cups)
• 1 teaspoon dry mustard
• 1 tsp onion powder
• 0.5 tsp ground coriander
• 1/4 tsp ground allspice
• 1/4 tsp ground cloves

Beer barbecue sauce

• 1/4 cup firmly packed dark brown sugar
• 1 tbsp tomato paste
• 1 bottle (0.33) stout, such as Guinness
• 1 tbsp. apple cider vinegar
• 0.5 tsp ground coriander
• 0.5 tsp dry mustard
• 1 teaspoon cornstarch

Burgers

• 220 g thin slices of corned beef
• 220 g of ground beef with 15% fat content
• 0.5 tsp dry mustard
• 2 tbsp unsalted butter, plus extra for greasing buns
• 8 slices Swiss cheese
• 4 potato buns, buttered and toasted if desired
• French fries, for serving

Preparation:

1. Caramelized onions:
   
   Heat a large skillet over medium-high heat. Add the butter, onion, 1 cup water, and 1/2 teaspoon salt. Cook, stirring frequently, until the onion is softened and most of the liquid has evaporated, about 12 minutes. Add the dry mustard, onion powder, coriander, allspice, cloves, 1/4 cup water, and 1/4 teaspoon black pepper. Cook, stirring occasionally, until the onion is browned and fragrant, about 5 minutes. Remove from the skillet, cover with foil to keep warm, and set aside. Do not wash the skillet.
2. Beer barbecue sauce:
   
   Add the sugar and tomato paste to the same skillet, spreading the mixture into an even layer. Cook until the paste begins to bubble, 30 seconds to 1 minute. Add the beer and scrape up any browned bits from the bottom of the pan with a wooden spoon. Stir in the vinegar, coriander, dry mustard, and 1/2 teaspoon salt. Bring the sauce to a simmer and cook until reduced by about a third, about 5 minutes. Meanwhile, whisk the cornstarch with 1 tablespoon of water in a small bowl until smooth and lump-free. Stir the mixture into the sauce and simmer until it coats the back of a spoon, about 2 minutes more. Set aside.
3. Burgers:
   
   Cut the corned beef into 2-inch (5-cm) pieces and place in the bowl of a food processor. Pulse until the meat is finely chopped, slightly larger than peas, then transfer to a large bowl. Using your hands, break the ground beef into small pieces and arrange them on top of the corned beef. Add dry mustard, 1 teaspoon salt, and 1/2 teaspoon black pepper and gently mix everything together with your hands, distributing the ingredients evenly. Form the meat mixture into four 1-cm-thick patties.
4. Place a large cast-iron skillet over medium-high heat. Add the butter and melt. Once the bubbling subsides, place the patties in the skillet and press gently with a spatula. Cook without moving until the edges are golden brown, 2-3 minutes. Flip. Top each patty with 1/3 cup of caramelized onions.
5. Place 2 slices of cheese on each patty, letting them hang over the sides of the onions. Cover the pan and cook until the cheese is completely melted and coats the patty, about 2 minutes. Remove the lid and continue cooking until the edges of the cheese are laced, about 1 minute more. To toast the potato buns, spread 2 tablespoons of softened butter on the cut sides. Place them butter-side down in a dry skillet and cook over medium heat until the buns are golden brown, about 3 minutes.
6. Innings:
   
   Place the burgers on the bottom bun halves. Spread a generous amount of barbecue sauce (about 60g per burger). Top with the top bun halves. Serve immediately with fries drizzled with barbecue sauce.
   
   Note
   
   If you don't have any leftover cooked corned beef, you can find it in the deli section of your supermarket.