- 3 tablespoons unsalted butter, divided
 - 1 bacon slice, cut into 1-inch pieces
 - 1/2 cup chopped white onion
 - 1 cup drained sauerkraut (5 ounces), rinsed
 - 1/3 cup dry white wine
 - 2 1/2 cups chicken stock or reduced-sodium chicken broth
 - 1/4 cup heavy cream
 - 1 teaspoon Dijon mustard
 - 2 teaspoons sour cream
 - 1/2 teaspoon all-purpose flour
 - 1 teaspoon sumac
 - 1/2 teaspoon sweet smoked paprika (pimentón dulce)
 - 1/4 teaspoon ground coriander
 - 1/4 teaspoon white pepper
 - Rounded 1/8 teaspoon cayenne
 - 1 teaspoon kosher salt
 - 12 large sea scallops, tough ligament removed from side of each if attached
 - 2 tablespoons olive oil
 - Garnish: baby arugula
 
- Melt 1 tablespoon butter in a 5-quart pot over medium heat, then cook bacon and onion, stirring occasionally, until most of bacon fat is rendered, about 5 minutes. Add sauerkraut and wine and simmer briskly, uncovered, until most of wine has evaporated, about 3 minutes.
 - Stir in stock and heavy cream, then simmer gently, uncovered, stirring occasionally, 20 minutes.
 - Remove from heat and stir in mustard, sour cream, and remaining 2 tablespoon butter. Purée soup in batches in a blender until smooth and creamy (use caution when blending hot liquids), then return to pot. Season with salt and pepper. Keep warm.
 - Mix flour, spices, and kosher salt in a bowl. Pat scallops dry, then generously coat one side of each scallop evenly with spice mixture.
 - Heat oil in a 12-inch heavy nonstick skillet over medium-low heat until it shimmers. Cook scallops, plain side down first, turning once, until just cooked through, 5 to 6 minutes total. Reserve spiced cooking oil.
 - Divide soup among 6 bowls. Place 2 scallops in each bowl and top with arugula. Drizzle soup with reserved oil.