French Onion Soup Burger

Ingredients:

Onion jam

• 3 large red onions, sliced ​​into 1cm thick rounds.
• 2 large cloves garlic, thinly sliced
• 6 tbsp. l. rapeseed oil (canola)
• 2 tbsp. l. dry marsala
• 1 tbsp dark brown sugar
• 1 tbsp Dijon mustard
• 1 tbsp red wine vinegar

Burgers

• 700 g of ground beef for burgers, 15% fat
• 2 tbsp. l. dry marsala
• 2 tablespoons lightly salted soy sauce
• 1 tbsp Worcestershire sauce
• 3 cups grated Gruyere
• 2 cups rich beef broth
• 4 potato sesame seed hamburger buns
• 8-12 thick slices of pickled cucumbers

Preparation:

1. Onion jam:
   
   Heat a large skillet, then add the onion and garlic along with 2 tablespoons of oil and a generous pinch of salt. Cook over medium heat for 2-3 minutes, then add the wine, brown sugar, and mustard and cook, stirring occasionally, until the onions are caramelized and soft, 20-25 minutes. Take your time with this step, as properly caramelized onions are the key to a great burger! Add the vinegar and cook for 1-2 minutes. Set aside.
2. Hamburgers:
   
   In a medium bowl, mash the ground meat. Season with salt and pepper. Gently stir in the wine, soy sauce, and Worcestershire sauce. Do not compact the ground meat or overmix it. The longer you mix it, the tougher the patties will be. Form 4 patties about 2 cm thick and place them on a baking sheet.
3. Using a spoon, carefully scoop out a small amount of meat from the center of each patty to create a well. Fill the well with about 1/4 cup of Gruyere. Flatten the scooped-out meat and press it into the cheese, sealing it in the center of the patty. Flip the patty over, seam-side down. Repeat with the remaining patties. Refrigerate for at least 30 minutes and up to 6 hours.
4. Preheat oven to 200°C.
5. Heat a large skillet over medium heat and add the remaining 4 tablespoons oil. Sprinkle the patties lightly with salt. When the oil begins to smoke, add the patties in a single layer, cheese side down, spacing them apart. Cook without moving them until browned on the bottom, 3-5 minutes. Flip the patties over and cook for another 3-5 minutes. Reduce the heat, add the broth to the skillet, and cover. Simmer until the patties are cooked through, another 8-10 minutes. Remove the lid, turn off the heat, and let the patties rest in the skillet.
6. Place the bun halves in a single layer on a baking sheet and sprinkle each half with about 1/4 cup of Gruyere. Place the baking sheet in the center of the oven and toast the buns until golden brown and the cheese is bubbling and melted, 5-8 minutes. Season with salt and pepper.
7. Raw buns:
   
   Lay the bottom halves of the buns flat. Mix the onion jam and remaining Gruyère into the remaining fat in the pan. Taste. Spoon some onion and liquid onto the bottom buns, top with the patties and some more onion. Add a few dill pickles and season with salt. Close the burgers and serve.