Combine vermouth, shallots, juniper berries, and peppercorns
in heavy small saucepan. Boil until liquid is reduced to 1/4
cup, about 12 minutes. Add clam juice and boil until reduced
by half, about 8 minutes. Add cream and boil until mixture is
reduced to 3/4 cup, about 8 minutes. Add butter 1 tbsp at a
time, whisking until melted before adding more. Strain sauce
through fine-meshed strainer. Return to saucepan. (can be
made 2 hours ahead. Keep at room temperature.) Heat oil in
heavy large skillet over medium-high heat. Sprinkle salmon
with parsley, then salt and pepper. Add salmon to skillet and
saute until just cooked through, about 4 minutes per side.
Meanwhile, rewarm sauce. Stir in olives, gin and lemon juice.
Season sauce to taste with salt and pepper. Place salmon on
plates. Drizzle sauce over. Garnish with chives and serve.