Ingredients

• 2 tablespoons butter
• 1 large onion, quartered lengthwise then thinly sliced
• Splash water
• 2 tablespoons spicy mustard
• 1 pound sack sauerkraut, rinsed and drained
• 3/4 cup sour cream
• 1/4 cup ketchup
• 1/4 cup pickle relish
• 1 1/2 pounds ground pork or ground pork and veal combined
• 1 teaspoon dried marjoram
• 1 teaspoon ground ginger
• 1/2 teaspoon freshly grated nutmeg
• 1 teaspoon celery seeds
• 1/2 teaspoon ground cardamom
• 1/4 cup finely chopped fresh flat-leaf parsley
• 2 tablespoons cider or white wine vinegar
• Kosher salt and freshly ground black pepper
• 1 tablespoon extra-virgin olive oil
• 4 deli slices Emmentaler Swiss cheese, folded to fit burgers
• 4 seeded or plain burger rolls, split
• 4 leaves red leaf or red romaine lettuce

Instructions

1. Heat medium skillet over medium heat, add the butter and when melted add the onions and cook until soft and tender, 20 minutes. When done, add a splash of water and stir in the mustard.
2. Add sauerkraut to a small pot and keep warm over low heat.
3. Combine sour cream, ketchup and relish in a small bowl and reserve.
4. In a large bowl, combine the meat, spices, parsley, vinegar and salt and pepper, to taste. Form 4 patties, thinner at middle and thicker at edges for more even cooking and to prevent burgers from bulging at the middle. Heat the oil in nonstick skillet over medium-high heat. Cook patties 5 minutes on each side. Melt the cheese over the patties the last 2 minutes of cooking, under foil tent.
5. To serve, pile the onions on the bun bottoms and top with a leaf of lettuce, cheese wurst burger, sauerkraut, and the sour cream sauce. Cover with the tops of the buns and serve.