Dry roast the coriander & cumin seeds in a frying pan for 5 minutes until toasted, then crush them in a pestle and mortar.
In a thick-based saucepan make the caramel syrup by dissolving the 10 tablespoons of sugar in 5 tablespoons of water and stir occasionally. When the sugar has dissolved, raise the heat and bring to the boil. DO NOT STIR.
Boil until the syrup becomes a light caramel colour. Take off the heat and add add 5 tablespoons of cider vinegar. Beware.. it will spit!
Add the sliced onions and crushed spices and stir.
Cook over a medium heat for an hour, or until the onions are soft.
When cool, store in an airtight container in the fridge.
Will keep for a month.
It is delicious served with a cheese board, smoked meats and cheese on toast. It is also ideal for topping canapes.