With a mixer, beat icing sugar and yolks until pale in colour. In a separate bowl and with clean beaters, whip cream until soft peaks form. Cook strawberries and rhubarb on stove until soft. Combine gelatin and cold water in small dish. Once set, add to strawberry-rhubarb mix. Fold in egg mix, then fold in whipping cream. Pour into desired mould, or pour onto baking sheet, and freeze. Cut out desired shape and, before serving, roll in white chocolate shavings or toasted crushed nuts.