Crush the blackberries a little, bring to the boil briefly in a saucepan with sugar and pass through a fine sieve. Soak gelatine, mix fruit pulp with yoghurt and juice of half a lime.
Squeeze out gelatine, mix with 2 tablespoons of yoghurt mixture, dissolve while slowly warming up. Fold the gelatin mixture into the yoghurt mixture, whip the cream until stiff and fold in as well. Chill in the refrigerator for at least 4 hours and then.
By the way, it also tastes good with blueberries or raspberries.
Cut the second half of the lime into thin slices and use as a decoration.