1kg rhubarb, washed and diced
500g onions, peeled and chopped
500g sultanas or raisins
600g malt vinegar
1-3 tsp dried chilli flakes
1 tsp salt
Spice bag; 1 thumb-sized piece of fresh ginger roughly chopped, 12 cloves, 12 black peppercorns, 1 heaped tsp coriander seeds, a few blades of mace
Put everything into a large heavy bottomed pan. Heat gently to dissolve the sugar and then slowly bring to the boil. The recipe I loosely based this on said simmer for 2-3 hours until so thick that you can see the base of the pan when you draw a wooded spoon through it. But I couldn't be bothered and bottled mine after an hour so it has a looser consistency.
When ready, seal in sterilised jars with vinegar proof screw lids (plastic coated on the inside to stop the vinegar corroding the metal!). Leave to mature for 6-8 weeks!