Rhubarb is a joy to make jam with, but it’s tartness and tendency to be watery when boiled means you need to do a 50/50 mix of fruit to sugar. This means you can end up with a very sweet jam. There are a few ways around this. Add a bit of ginger, whose heat distracts from the sugar, or add lemon juice at the end of making the jam. In this case add grapefruit whose bitter-sweetness balances the sugar beautifully. This recipe is a part jam, part marmalade.
This rhubarb comes from the back garden of my house in Peckham. The rhubarb crown is in it’s third year and really flourishes against the brick wall at the bottom of the garden.
2kg Rhubarb, picked, washed and chopped
2kg jam sugar
1 white grapefruit
4 lemons, juiced
Mix the rhubarb with sugar and leave till all the sugar has dissolved into a lovely thick syrup around the rhubarb. Takes about 2 hours.
Put the whole grapefruit into a pan of boiling water and boil for around 1 hour, till the skin of the grapefruit just begins to split. Remove from the water, scoop the flesh and roughly chop discarding pips. Thinly slice the skin.
Boil the rhubarb and sugar mix with the cut grapefruit in a large pan as vigorously and rapidly as you can – but watch out for it boiling over the side. Make sure you stir from time to time, and after 20 minutes keep a very close eye – it has a tendency to stick to the pan. Test for the setting point by putting a small blob of jam on a cold plate – when the jam ripples when pushed with a finger, add the lemon juice.
Pour the hot jam into sterilised jars and seal straight away. Let settle for a couple of weeks and then tuck in.