Pour 1/2 cup cold water over the gelatin and leave it to swell.
In a bowl, mix the yoghurt, sugar, lemon zest and juice. Stir until the sugar dissolves.
Melt the gelatin without boiling it in a container in a water bath on the stove. Then pour it in a thin trickle into the yoghurt and stir.
Put some fruits of your choice at the bottom of dessert cups or bowls and pour on the cream. Put them in the fridge for at least 4 hours to gel.
When serving the creams, dip the cups for a few seconds in hot water and invert onto plates.