Rhubarb Ice Cream
300ml (10½fl oz) cream, softly whipped - this should come to about 500ml (17½ fl oz) whipped cream
Put the sliced rhubarb, the 50g (2oz) sugar and the tablespoon of water in a small saucepan on a medium heat. Stir to dissolve the sugar. Bring up to the boil, then reduce the heat to medium-low and cook for a few minutes until the rhubarb is soft and tender. Stir in the lemon juice. Then pour the rhubarb out on to a plate and allow to cool.
Put the 250g (9oz) caster sugar and the 200ml (7fl oz) water in a saucepan on a medium heat. Stir to dissolve the caster sugar, then bring up to the boil. Increase the heat to high and boil fiercely for about 5 minutes until the mixture reaches the 'thread' stage. If you own a sugar thermometer, this is when it reads 106°C-113°C (223°F-236F). If you don't have a sugar thermometer, dip a metal spoon into the mixture; as you remove it, the last drops of sugar syrup will form thin threads if the correct temperature has been reached.
Meanwhile, using an electric whisk, whisk the egg whites along with the cream of tartar until they are stiff. Still whisking, gradually pour in the hot sugar syrup in a thin stream, and continue to whisk until the mixture is cool, glossy and stiff (this will take about 4 or 5 minutes). Fold in the cooked rhubarb mixture and the whipped cream, though not completely, as I like to leave this slightly marbled. Put in the freezer and freeze overnight. This ice-cream can be scooped straight from the freezer.