Ginger & grapefruit marmalade

1. Cut 2 grapefruit into quarters, then slice finely widthways. Put in a large pan and cover with water. Bring to the boil, then cook for 4-5 minutes or until the peel softens and starts to change colour. Drain, then return the softened slices to the pan.

2. Meanwhile, quarter the remaining 2 grapefruit and use a small serrated knife to slice the flesh away from the skin and white pith. Roughly chop the flesh and discard the peel.

3. Put the chopped grapefruit into the pan with the grapefruit slices. Add the remaining ingredients and 1.3L water.

4. Bring to the boil, then reduce to a simmer for 1 hour 30 minutes-2 hours, stirring occasionally, until thickened and syrupy. Take off the heat and set aside to cool for 20-30 minutes. Pour into sterilised jars, seal and label. Store in a cool, dark place for up to 3 months.