Place the beetroot, ginger and onions in a food processor and blitz until chopped but still quite chunky. You will have to do this in batches.

Place a splash of olive oil in a large, heavy-based pot. Use a cast-iron pot or a special preserving pan, as the vinegar might react with anything else. Add the mustard seeds and cook until they begin to pop. Then simply tip in all of the remaining ingredients. Stir well to ensure everything is combined. Bring to the boil then reduce the heat to low. Simmer uncovered for about 1½ hours, stirring occasionally, until the liquid becomes syrupy.

Remove the cloves if you can, then pot into warm sterilised jars. Seal with a lid and label. Once opened, eat within a week.