The sauerkraut in this elegant appetizer, a Berlin twist on oysters florentine, lends the dish a pleasing acidity that complements good champagne.
- 2 cups coarse sea salt
- 16 large oysters, such as wellfleet, bluepoint, or Apalachicola
- 5 Tbsp. butter
- 1 medium yellow onion, finely chopped
- 3⁄4 cup dry white wine
- 1⁄2 lb. sauerkraut, rinsed and drained
- Kosher salt and freshly ground white pepper, to taste
- 3⁄4 cup heavy cream
- 1 tbsp. dry vermouth
- 1 egg yolk
- Pinch of cayenne
Spread sea salt on a large baking sheet. Open oysters over a cheesecloth-lined sieve over a bowl to collect oysters' liquor. Remove oysters and chill. Discard flat top shells. Wash bottom shells and place on sheet; set aside.
Heat 3 tbsp. of the butter in a pot over medium heat. Add half the onions and cook until softened, 5-7 minutes. Add 1⁄2 cup of the wine, sauerkraut, and salt and pepper; boil. Reduce heat to medium; simmer, partially covered, 8-10 minutes. Drain the sauerkraut mixture and set aside.
Heat remaining butter in a pot over medium heat. Add remaining onions; cook until softened, 5-7 minutes. Add oyster liquor, remaining wine, 1⁄2 cup cream, and vermouth and bring to a boil. Lower heat to medium-low; reduce by half, about 20 minutes. Remove from heat; whisk in egg yolk and remaining cream. Add cayenne and season with salt and pepper. Set sauce aside.
Heat broiler with rack 4" from element. Divide sauerkraut between shells; top each with an oyster. Spoon some sauce over each and broil until light golden brown, about 5 minutes.