Mix the mustard and cumin seeds, the turmeric, crushed garlic, vinegar, salt and sugar together in a sterilized glass bowl.

Cover with a cloth and leave to rest for 24 hours. This enables the spices to infuse and the sugar and salt to melt.

Heat the mustard oil in a frying pan and gently fry the spice mixture for about 5 minutes (keep a window open while cooking with mustard oil as it is pungent and the smoke may irritate the eyes).

Add the garlic cloves and fry for a further 5 minutes.

Add the chilies and cook gently until tender but still green in color. This will take about 30 minutes on low heat.

Cool thoroughly, then pour into sterilized bottles, ensuring the oil is evenly distributed if you are using more than one bottle.

Leave to rest for a week before serving.