Pancakes:

• 1 pound baking potatoes, peeled
• 1 large egg, lightly beaten
• 1/4 cup matzo meal
• 1/4 cup grated onion
• Salt
• Vegetable oil, for frying

Scallops and Caviar Sauce:

• 1 1/2 cups Champagne
• 9 black peppercorns
• 3 thyme sprigs
• 1 bay leaf
• 1 large shallot, thinly sliced
• 1 teaspoon fresh lemon juice
• 1 1/2 tablespoons crème fraîche
• 1 1/2 sticks (6 ounces) cold unsalted butter, cut into tablespoons
• 1 ounce caviar
• Salt
• Vegetable oil, for frying
• 20 medium sea scallops (1 pound)
• 2 tablespoons minced chives

1. Coarsely shred the potatoes and squeeze out any excess liquid. Transfer to a large bowl and stir in the egg, matzo meal, onion and a large pinch of salt. Shape the mixture into 20 scallop-size cakes, about 1/2 inch thick; press the cakes to compress them.
2. In a large skillet, heat 1/4 inch of vegetable oil until shimmering. Working in batches, fry the pancakes over moderately high heat until browned and crisp, about 3 minutes per side. Lower the heat if the pancakes brown too quickly and add more oil if necessary. Transfer the pancakes to a baking sheet and sprinkle with salt.
3. Preheat the oven to 325°. In a small saucepan, combine the Champagne with the peppercorns, thyme sprigs, bay leaf, shallot and lemon juice and boil over high heat until reduced to 1 tablespoon, about 15 minutes. Strain the sauce into another small saucepan. Stir in the crème fraîche and bring to a simmer over moderate heat. Remove from the heat and stir in the softened butter, 1 tablespoon at a time. Stir in the caviar and season lightly with salt. Cover the sauce and keep it warm.
4. Wipe out the skillet and heat 1/4 inch of oil in it until shimmering. Season the scallops with salt and add half of them to the skillet. Cook over high heat until richly browned, about 1 1/2 minutes per side. Transfer to a plate and keep warm while you cook the remaining scallops.
5. Rewarm the potato pancakes in the oven. Arrange the pancakes on a platter and set a scallop on each one. Add the chives to the caviar butter sauce and spoon over the scallops. Serve right away.