Soak the gelatine in cold water. Separate eggs. Beat egg yolks and sugar until frothy. Add lemon juice. Dissolve the gelatine in two tablespoons of hot water and mix well with the lemon egg foam. Chill until the cream starts to set. Beat the egg white and a pinch of salt until stiff. Beat the whipped cream until stiff. Fold the egg whites and the whipped cream one after the other into the cream. Pour the cream into glasses and let it set in the refrigerator for at least 2 hours. Serve garnished with chopped pistachios.