Sweet and sour gets all the glory, though too often the sweetness overbears, stifling the flavour of everything else and leaving little sourness to detect. In Indonesia a hot-sour combo is more popular and works so well with duck. This sauce has it all - there are complex layers of flavour and a deep savouriness, it is smooth and luscious without being rich, and the punch of chilli heat and tamarind sour really shine through. Adjust to your taste, leaving as many chilli seeds as you dare wh