Marrow and Ginger Conserve Recipe

Method

1. First tackle your marrow: cut off its ends, then cut through the middle and set each half upright on one end before slicing off its thick skin. Quarter the peeled marrow lengthways and cut away and discard the seeds. Finally, cut the flesh into 2cm/1in cubes and weigh

2. Place the cubed marrow in a large mixing bowl with the sugar. Mix thoroughly. Use a julienne zester and finely zest and juice one lemon. Add to the sugared marrow. Cover and leave overnight – by morning, it will be swimming in liquid

3. The next day, scrape everything into a preserving pan. Roughly bash the root ginger with a rolling pin. Wrap the ginger into a square of muslin and tie into a bag. Place in the sugary liquid. Squeeze the juice from the remaining lemons and the grapefruit half and add to the pan

4. Sterilise your jam jars by washing them in hot soapy water, rinsing in very hot water, and then placing them in a cool oven, fan 130°C/gas 1 to dry. Alternatively, wash in the dishwasher, then leave to dry with the dishwasher door partially open

5. Clip a jam thermometer to the preserving pan. Set over a medium heat and stir regularly until all the sugar has dissolved. Bring slowly up to the boil and boil steadily until the marrow looks transparent and the syrup has really reduced and thickened – it should reach a little over 106°C/220°F on the thermometer. Discard the ginger. Pour into the hot sterilised jars. If using screw-top lids, wait until cold, then cover. Otherwise, cover with waxed paper discs and transparent covers.