2 tablespoons butter
1 large onion, quartered lengthwise, then thinly sliced
A splash of 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 flat leaf parsley, finely chopped
2 tablespoons cider or white wine vinegar
Kosher salt and freshly ground black pepper
1 tablespoon extra virgin olive oil (EVOO)
4 deli slices Emmentaler Swiss cheese, folded to fit burgers
4 seeded or plain hamburger buns, split
4 leaves red leaf or red romaine lettuce
Heat a medium size skillet over medium heat. Add the butter, and when melted, add the onion and cook until soft and tender, 20 minutes. When done, add a splash of water and stir in the mustard.
Add the sauerkraut to a small pot and keep warm over low heat.
Combine the sour cream, ketchup and relish in a small bowl and reserve.
In a large bowl, combine the meat, spices, parsley, vinegar and salt and pepper, to taste. Form four patties that are thinner at middle and thicker at edges for more even cooking and to prevent the burgers from bulging at the middle. Heat the EVOO in nonstick skillet over medium-high heat. Cook the patties for 5 minutes on each side. Melt the cheese over the patties during the last 2 minutes of cooking under a foil tent.
To serve, pile the sliced onion on the bun bottoms and top with a leaf of lettuce, burger, sauerkraut and the sour cream sauce. Cover with the tops of the buns and serve.