Soak gelatine in cold water. Skin mackerel, fillet and cut into pieces. Wash the dill. Puree mackerel, dill, lemon juice and crème fraiche. Season with salt and pepper.
Squeeze and dissolve the gelatine. Stir into the fish mixture. Whip cream until stiff and fold in. Chill for 30 minutes. In the meantime, clean and wash the lettuce and tomatoes. Pluck lettuce into pieces, cut tomatoes into slices.
Arrange on a plate. With the help of 2 teaspoons of the fish mousse, cut 12 small dumplings off and arrange them on the salad. Baguette tastes good with them.