In jams, pies, cobblers, and other sweet treats, rhubarb routinely gets paired with strawberries, for good reasons: Rhubarb and strawberries tend to reach the peak of their seasons together, and strawberries disguise the often lackluster color of rhubarb (although all-green rhubarb can be attractive on its own; see my recipe for Green Rhubarb Jam).
But in a spring as cool the one we’re experiencing in the Pacific Northwest now, local strawberries lag behind the rhubarb. There’s hardly a spot of red in the berry patches yet, and nobody wants to substitute hard, green-centered strawberries from California for sweet, tender red fruits from the garden or farm stand. This is a good time, though, to clean out the freezer, to make room for the abundance that will come (it will, really). And amid the pork chops and pesto may lurk bags and bags of last year’s fruit. My friend Sally hauls all out all her frozen fruit this time of year to make a batch of mixed-fruit wine. I make jam.
I decided to make jam from the last of last summer’s blueberries combined with the first of this year’s rhubarb. The pairing worked: The rhubarb took on the deep-blue color of the berries, lent an interesting texture, and balanced the berries’ high pectin content so I could use minimal sugar and yet avoid a tough gel. To eliminate the unpleasant fibrousness of cooked blueberries, I first heated the berries separately and then pressed them through a food mill. The result is a lusciously soft, dark jam that seems the essence of blueberry until you notice the tart yet subtle background note of rhubarb.
Supposing no blueberries turn up in your freezer, wait a few weeks. With adequate watering, your rhubarb will still be going strong when the first blueberries ripen. Then you can mix the two deliciously in jam—or in a pie, a tart. a crisp, or a cobbler.
1 1/2 pounds blueberries
1 pound trimmed rhubarb (leaves and tough bases cut off), cut into small pieces
3 1/3 cups sugar
2 tablespoons lemon juice
If the berries are frozen, let them thaw.
In a broad, heavy-bottomed pan, simmer the blueberries, covered, for about 5 minutes. Press them though the fine disk of a food mill.
Combine the berry purée in the pan with the rhubarb, sugar, and lemon juice. Cook the mixture over medium heat, stirring, until the sugar has dissolved. Raise the heat to medium-high, and boil the mixture, while still stirring frequently, until the rhubarb breaks down and a bit of the jam mounds in a chilled bowl, or until the temperature of the mixture reaches 221 degrees F. This should take no more than 10 minutes. Remove the pan from the heat.
Skim the foam from the jam, and ladle the jam into sterilized half-pint mason jars, leaving 1/4 inch headspace. Close the jars, and process them for 5 minutes in a boiling-water bath.
Remove the jars to a rack or pad, and let them stand undisturbed for 24 hours, after which time the jam should be well set. Store the jars in a cool, dry, dark place.
Makes about 6 half-pints