Put the apricots, water, caster sugar and vanilla-pod in a medium saucepan and bring to the boil.
Allow to simmer gently, uncovered, for twenty-five minutes. The mixture will reduce by about one-third, giving a moist, thickish purée. Stir frequently as it cooks to prevent the apricots from sticking.
Take out the vanilla-pod, put the mixture in the liq