Soak the red and white gelatine separately in plenty of cold water. Mix buttermilk, sugar, lemon peel and juice until the sugar has dissolved. Squeeze the red gelatine and dissolve in a saucepan over a low heat.
Stir under half of the buttermilk and chill. In the meantime, whip cream until stiff. Put 4-5 tablespoons aside for decorating. As soon as the pink buttermilk cream begins to set, fold in half of the cream with a whisk.
Place the dessert glasses at an angle and pour in the pink buttermilk cream. Chill for about 1/2 hour until firm. Squeeze out the white gelatine, dissolve it as well and stir into the remaining buttermilk.
Cold until it begins to set. Fold in the rest of the cream and pour into the upright glasses. Refrigerate again for about 1/2 hour. Fill the remaining cream for decoration into a piping bag with star spout and spray one tuff each onto the cream.
Serve decorated as desired with lemon slices and lemon balm.