Potato Pancake with Salmon and Caviar

To prepare the pancake batter: Cook the potatoes in boiling salted water until soft. Peel and put in a large bowl. Break up and mash with a wooden spoon. Mash in the flour. Mash in the egg yolks in two additions. Switch to a whisk and beat in the egg whites, again in two additions. Add the cream and whisk until the mixture is the consistency of pastry cream. Set aside.

To prepare the sauce: Zest the lemon and place the zest in a heatproof bowl. Set the rest of the lemon aside. Pour boiling water over the zest. Let stand 30 seconds; drain. Repeat twice. Set aside. Put 1 tablespoon of the butter in a medium saucepan over medium heat and let melt, then stir in the shallots. Cook until the shallots have softened, 1 to 2 minutes, then stir in the vinegar and wine. Cook until the liquid is reduced by half. Stir in the cream, reduce the heat to medium-low, and cook 1 minute. A bit at a time, whisk in the butter, moving the pan on and off the heat to keep the temperature low enough to let the butter melt and incorporate, but not so hot it melts the entire sauce. If yellow streaks appear, take the sauce off the heat and quickly whisk in several cold pieces of butter until the sauce recombines. Strain through a fine-meshed sieve. Season with salt and pepper. Set aside and keep warm over warm water.

To prepare the pancakes with salmon: Trim the salmon to make eight 2-1/2-inch squares. Place four squares on a work surface and put a small spoonful of caviar on each. Top with the remaining squares to make four “sandwiches.” Set aside.

Heat half the clarified butter in a large saute pan or skillet over medium-high heat. Drop the pancake batter by large spoonfuls into the hot butter; the pancakes should measure about 4 inches in diameter. Make a total of at least 4 pancakes; cook in batches if necessary. Cook 30 seconds, then gently place a salmon sandwich on the center of each pancake. Continue cooking until the edges of the pancakes show a little brown color. Add more butter as necessary so the pancake bottoms are immersed in butter. Turn each, putting the salmon on the bottom, and cook another 2 to 3 minutes, until done through. Take off the heat. If you have extra pancakes, cook them without the fish and set aside to cool; separate with waxed paper or parchment circles, wrap, and freeze for another use.

To serve: Squeeze the lemon to extract the juice and strain into the sauce. Add the lemon zest; stir or swirl to blend. Arrange two tomato diamonds at the 12 o’clock and 6 o’clock positions on each serving plate, and place a bit of frisee between the diamonds toward the rim of the plate. Pool sauce in the center of each plate and top with a pancake, fish-side down.