In the bowl of a food processor, combine the fruit, salt, sugar, and pepper and process to a paste.
Center a 2 by 3-foot piece of cheesecloth in a non-reactive baking dish or plastic container large enough to hold the fish flat, about 9 by 13 inches. Pack half of the citrus-salt mixture onto the skin-side of the fish, spreading out to the edges, and top with half of the herbs. Place the fish skin-side down in the middle of the cheesecloth and spread the remaining salt mixture and herbs over the flesh. Fold the cheesecloth in over the fish and carefully roll and turn the fish over into the cheesecloth to completely enclose.
Top with a second large non-reactive baking dish. Place weights or large heavy cans on the second dish to weight and press the fish. Let cure in the refrigerator for 48 hours, turning once.
Remove the weights and top baking dish and place the fish on the work surface. Discard the wrap and scrape the remaining salt and herb mixtures from the fish. Rinse the fish under cold running water for 1 minute to remove any remaining mixture and gently wipe dry with paper towels. Wrap in plastic wrap, place on a platter, and freeze until firm enough to slice easily, 30 to 45 minutes. (Alternatively, refrigerate until ready to slice.)
Remove the fish from the freezer and slice the salmon as thinly as possible at a slight angle. Arrange the slices decoratively on the platter and serve with the Lemon-Caper Cream Cheese Spread and the Chive Blinis. (Alternatively, blinis may be spread with the Lemon-Caper Cream Cheese Spread and then topped with a small piece of gravlax and passed or plated as hors d'oeuvres. Garnish with fresh dill or chives before serving.)
Place all the ingredients in a medium bowl and cream together using a rubber spatula or heavy wooden spoon. Spoon into a decorative bowl and serve immediately.
Dissolve the yeast in 1 cup of the warm milk and add 1 teaspoon of the all-purpose flour. Place the mixture in a warm place until it rises and doubles in size, about 10 minutes. Add the rest of the warmed milk. Sift in the remaining all-purpose flour and the buckwheat flour. Add the sugar, 3 of the egg whites, the butter and the chives. Beat until smooth. Cover the bowl with plastic wrap and set aside to rise until doubled in size, about 1 hour. Stir the mixture lightly and let it rise again for 30 minutes.
Whisk the remaining egg whites until frothy and add to the mixture. Heat a nonstick skillet over medium-high heat and spray with nonstick cooking spray (or lightly brush with butter). Drop tablespoonfuls of batter into the skillet and cook until bubbles form and blinis are golden brown on the bottom, 30 seconds to 1 minute. Turn blinis and cook until golden brown on the second side, 30 seconds to 1 minute.
Blinis may be made in advance and frozen, wrapped well in plastic wrap and placed inside a resealable food storage bag.