Summer Rhubarb-Strawberry Jam

Rhubarb strawberry jam is the classic two-fruit pairing that defines early summer preserving. The tartness of rhubarb and the floral sweetness of fresh strawberries come together in a jam that tastes brighter and more complex than either fruit could pull off alone.

The rhubarb gets a quick simmer in water before joining the crushed berries. That softening step matters because rhubarb stalks are fibrous and won’t break down enough during the short jam boil. Don’t peel the stalks, that’s where most of the rosy color lives.

Liquid pectin needs a hard one-minute rolling boil after the sugar dissolves. That high heat activates the pectin and triggers the set, which is why you need a big saucepan, the mixture foams up dramatically. Skim the foam quickly off the surface for the clearest, prettiest jars.

Water-bath canning seals everything for the pantry. Five minutes in boiling water is enough for a proper seal, and the jars will keep for a year in a cool, dark spot.

Pro Tips

• Measure the sugar exactly. Pectin recipes are chemistry, and too little sugar means a jam that won’t set.
• Use a wide, deep saucepan, the boil expands the volume by three or four times in the moment of full boil.
• Have your jars hot and ready before starting, the jam needs to go in immediately to seal properly.
• Skim foam with a metal spoon, plastic catches and smears it.

Variations

• Add a teaspoon of finely grated orange zest with the fruit for a citrus brightener.
• Swap a cup of strawberries for raspberries for a more berry-forward version.
• Add a split vanilla bean to the simmering rhubarb for a vanilla-strawberry-rhubarb jam.