Smoked Salmon and Mackerel Canapes

In a bowl, soften the gelatin in cold water. In a food processor, puree the mackerel fillets with the double cream and season with salt and pepper. Transfer to a bowl.

Dissolve the soaked gelatin in a small saucepan over low heat. Stir in a little of the mackerel mixture, then fold the mixture back into the remaining mackerel mixture. Fold the smoked salmon and dill into the bowl. In a separate bowl, whip the cream to stiff peaks and gently fold it into the fish mixture.

Place the pumpernickel, 2 by 2 on a large board and place a frame around it to keep the fish mousse from running over. Spoon the fish mixture on top of the bread and smooth. Cover and refrigerate until set,  3 - 4 hours.