Soften gelatin in 1/2 cup of the fish stock.
Heat wine, remaining stock and onions to boiling.
Reduce heat and simmer for 5 minutes.
Remove from heat.
Add gelatin and stir until dissolved.
Add clams with liquid, lemon juice, capers and a few drops of Tabasco.
Refrigerate until set.
Spoon into serving dishes.
Garnish with a dollop of sour cream, a spoonful of caviar and lemon wedges.
Makes 8 to 10 servings.