Serve these hearty, German-style stacks with sauerkraut and frothy microbrews. Is that a polka I’m hearing?
Note: The sauteed onions can be prepared ahead. Let them stand at room temperature or refrigerate them, if it will be longer than an hour before serving time. Warm them over low heat prior to sandwich assembly.
1. Pre-cook bratwurst in beer according to directions on package.
2. Heat olive oil in one large or two medium-large heavy skillets over medium-high heat. Add onions and sauté until slightly softened, about 5-10 minutes. Stir in vinegar and honey. Reduce heat to medium-low and sauté until onions are deep brown and very tender, about 20 minutes longer. Season to taste with sea salt and pepper.
3. Heat broiler or grill. Place pre-cooked brats in an oiled metal pan. Broil until sausages are brown and crisp, about 6 minutes per side. Transfer brats to a work surface and cut them lengthwise in half.
4. Arrange 2 brat halves on each of 4 bread slices. Spread 2 teaspoons mustard over brats on each. Top sausages with caramelized onions. Then top with baby Swiss cheese slices. Cover with remaining 4 bread slices. Spread half of butter over upper bread slices.
5. Heat a large, heavy skillet over medium-low heat. Carefully invert sandwiches, buttered side down, onto skillet. Cover and cook until bottoms are toasty brown, about 5 minutes. Spread remaining butter over upper bread slices. Carefully turn sandwiches, cover and cook until bottoms are brown, about 4 minutes longer.