Put all the ingredients, except the curry leaves, into a large preserving pan with 2 tsp sea salt, 1 tsp freshly ground black pepper and 500ml water. Mix well and bring to a simmer. Cook on a medium heat for 1 hr 45 mins-2 hrs, without a lid, until the squash is tender and the mix is significantly reduced and glossy. Add the curry leaves 15 mins before the end of cooking.

Spoon the pickle into eight sterilised jars and tightly seal the lids. Will keep for six months unopened and chilled for six weeks after opening. Best left to mature for at least one week before serving.