Step 1 Combine all the ingredients in a pan over a medium heat. Bring to the boil while whisking, ensuring the sugar dissolves.

Step 2 Reduce the heat and allow the mixture to simmer until it reduces to the right consistency - it should coat the back of a spoon easily.

Step 3 Taste and adjust the seasoning - you might want a little more acidity, in which case add more vinegar. Or perhaps a bit more sweetness - that could come from honey or maple syrup perhaps? Play with spices - you could add star anise for depth of flavour.