Soften the gelatin in the cold water, add the boiling water and stir until the gelatin has dissolved. Cool. Add the mayonnaise, lemon juice, onion, tabasco, paprika and salt and mix well. Chill to the consistency of unbeaten egg white. Add the salmon and capers and beat well. Whip the cream, fold into the salmon mixture and turn into a 2 quart oiled fish mold. Add the cheese to fill the mold. Chill until set. Unmold on a serving platter and garnish with watercress, lemon slices and salmon roe. Serve with sour cream dill sauce.