This might sound like a rather strange fruit combination, a doubling down on the sour and bitter, and I certainly agree, if you’re a fan of neither taste, then this jam isn’t for you! For those who are however, it is the most incredible combination, with the distinctive tang of the rhubarb interspersed with bites of tender citrusy peel, and visually, despite my failure to capture it in good light, its the most wonderful swirling pink and orange – a stormy sunset of a jam. Note this is with ruby grapefruit, the colour isn’t as good without.

The texture, because of the rhubarb contributing its slightly thready pulp, is not quite like a normal jam and doesn’t exactly gel – however it will still clearly thicken until it dollops from the spoon, and is perfectly spreadable. And you could certainly have it on toast or scones like any jam, but because of the almost stewed fruit like texture, plus the strong flavour, I think its best combined through other things -with ricotta, swirled through yoghurt, on pancakes etc.

My absolute favourite way to eat it though, and a perfect way of getting through the 10 jars!, is to tip an entire jar into a pile of sliced apples and make my favourite apple crumble – with perfect sweetness and amazing complexity of flavour from just two ingredients. (and yes, that recipe is hopefully soon on my list now on the blog)

The process, as with most of my preserve recipes, might seem very long, but can be done in short bursts over a few days – I describe it over two days, but there’s no reason you couldn’t prepare the grapefruit one weekend, and make the jam the next. You might wonder why you can’t just cook it all up together, but grapefruit rind really takes a while to soften compared to the rhubarb, so if you don’t precook, you could end up with either hard bits of peel, or burnt rhubarb. It really is straightforward I promise, so give it a go and you to can have sunset in a jar 🙂

Rhubarb and grapefruit jam

Adapted from a recipe in Jane Grigson’s Fruit Book

  • 1.1kg rhubarb stalks
  • 1.1kg white sugar
  • 4 grapefruit (approx 1.1kg)

Day 1

Wash and trim the rhubarb, and cut into 3-4cm lengths. Place in a large saucepan, and pour over the sugar. Cover with a lid and leave overnight.

Scrub and halve the grapefruit and juice them. Reserve the juice in the fridge. Put the juiced halves in a medium saucepan and cover with cold water. Bring to the boil and cook for five minutes, then drain. Repeat this process, then cover with water and bring to the boil again, but this time reduce the heat and simmer for about an hour until the rinds are completely tender.

Allow the grapefruit halves to cool, and then use a tablespoon to scoop out the remaining pulp, and also scrape the pith (white part) until you have a thin even rind (see above). Chop well and reserve the scraped pulp. Cut each half rind in half again, and then slice each quarter across into thin slices. Refrigerate the slices and pulp overnight.

Day 2

Sterilise 12 8oz jars (I always do a couple extra) and put a saucer and teaspoon in the freezer to test the set.  The method I use to sterilise is here.

Add the grapefruit juice, pulp and sliced peel to the rhubarb and sugar and stir well. Heat gently until sugar has completely dissolved.

Once the sugar is dissolved, bring the mixture to a boil over high heat and continue boiling rapidly for about 20 min.  As the water evaporates and the sugar concentration increases it will foam a bit, and may start to spit as it thickens, so don’t walk away, and be prepared to turn the heat down.  Stir regularly with a wooden spoon or silicon spatula to ensure the bottom isn’t sticking. Towards the end you might want to wear an oven mitt so you don’t get splashes on your hand.

After 20 min, or when it’s thickened and the rhubarb is largely broken down, pour a small amount in the chilled spoon and put back in the freezer on the saucer for a couple of min.  You may need to test a few times.  When the cooled liquid turns is thick and drops slowly from the spoon (ie like jam), it’s done.  

Turn off the heat and stir again to make sure the grapefruit peel is distributed evenly.  Ladle the jam into the sterilised jars, tighten the lids and cool.  I’m writing this now to the gentle popping sound of the lids as they seal!

Makes about 10 jars depending on size