Chinese Plum Sauce

This is the second of the sauces I made when I had a problem with my back. I tried this on a stir fry a couple of nights ago and it's a little bit vinegary for my tastes, so if I make it again I will reduce the amount of vinegar. I'd also like to try it on crispy duck pancakes to get a real sense of it's flavour.

I'm also not convinced that this will make 2.5l. I halved the recipe and only got a 500ml bottle, which is fine for me but not what the recipe said.

Chinese Plum Sauce (from Waitrose)
(Makes 2.5l)

3 onions, finely chopped
50g fresh root ginger, finely grated
4 garlic cloves, finely chopped
2 red chillies, finely chopped
2.5kg plums, stoned and quartered
1 litre white wine vinegar
250g light soft brown sugar
200ml light soy sauce
½ cinnamon stick
3 star anise

Put the onions, ginger, garlic, chilli, plums, vinegar and 300ml water in a large pan. Simmer for 20 mins, until soft. Sieve, pushing with a wooden spoon to extract all the pulp and liquid.

Return the strained liquid to the pan with the sugar and soy sauce and bring back to the boil. Add the cinnamon and star anise. Simmer, uncovered, for about 11/2 hours, stirring occasionally, until thick. Remove the spices, pour into sterilised bottles, seal and cool.

Store in a cool, dark place for up to 4 months. Once opened, keep refrigerated and use within 3 weeks.