Wash the aubergines and pat dry. Slice the aubergines and place in a heavy bottomed pan along with the onions and salt. Also add the tomato paste and stir well to combine.

Cook for a minute or two and then add the vinegar and sugar; mix well and then add the sultanas, chilli flakes, cayenne pepper, cinnamon, ginger and Nigella seeds. Stir well and cook on medium heat till the sugar has almost dissolved. Turn the heat up and bring to boil.

Reduce the heat to the lowest possible, cover the pan and simmer gently for 30 minutes.

Open the pan and continue to cook on low heat stirring occasionally so that the mixture does not burn or stick to the bottom of the pan. The chutney is ready when it has turned thick and sticky; also taste and make sure that the vinegar has been absorbed well or it will taste acidic.

Remove the cinnamon stick and allow to cool well. Ladle into sterilized jars with tight lids. Refrigerate.