Blubarb Jam: A Sweet and Slippery Slope

If you’re new to making fruit preserves, blueberries are the perfect gateway. Widely available, rich in their own pectin, and relatively inexpensive, blues are a small-batch-friendly fruit. And with no hulling and no pitting, your prep is pretty much limited to a quick rinse and a scan for stray stems and bum berries.

Boxing Day
Despite all our recent rain, the CSA’s blueberries have been super sweet so far this season.

Lovely when sugared and cooked on their own, they also take well to add-ins like sour cherries, raspberries, rhubarb, vanilla, cinnamon, cardamom, rosemary, thyme, lemon, sage, and lots more. Experiment till you find your own groove(s). That’s the beauty of working small.

Blubarb Jam

If you don’t have (or don’t like) rhubarb, sub in sour cherries. Or go full-on with the blueberries and reduce the sugar by a quarter cup. Yields a little over 2 pints of preserves. 

  • 5 cups blueberries, picked over and rinsed
  • 2 cups chopped rhubarb
  • 3 cups granulated sugar
  • 1/2 vanilla bean, split
  • 1/4 tsp ground cinnamon
  • juice of 1 medium lemon

Combine the berries, rhubarb, and sugar in a large pot. Slowly bring the fruit mixture to a boil until the juices are clear—probably 5-10 minutes. Remove from heat. Scrape the vanilla seeds into the pot, then add the beans. Cover loosely, and leave it alone to macerate further for at least four hours. I generally flash-cook the fruit after dinner, let it sit overnight, then cook and jar the jam in the morning before I go to work.

Little Jars
It’s that time of year: my shelves full of empty little jars are slowly becoming shelves full of full little jars.

When you’re ready to jam, prepare your jars and lids by sterilizing them in boiling water for 5 minutes. If you’re not confident about picking up the visual cues for when jam is “done,” now’s the time to tuck a small plate in the freezer. I’ll explain later.

Pick out the vanilla bean, then stir in the cinnamon and lemon juice. Scoop three or four ladles of the fruit-sugar mixture into a large skillet. Yep, a skillet, not a big saucepan. Working with small portions in a big, wide pan means the fruit’ll hit higher temps faster, coming to the jell stage while it still tastes fresh. And do yourself (or your dish helper) a favor: use a non-stick pan. The first time I made jam this way, I didn’t even own one. I do now.

Over medium-high heat, bring the mixture to a simmer and cook until it thickens. Depending on how juicy the fruit is, this’ll take 5-10 minutes at a full-on, bubbling simmer. With some experience, you’ll be able to judge when it’s done by how it looks and feels (and sounds, honestly).

Swipe your spoon or scraper through the mixture quickly; when it’s ready, you’ll see distinct “walls” on either side that’ll take just a beat or two to fill in behind the path you leave. I let this pan above go for just one more minute, and the set, after everything cooled, was a beautiful balance of firm and spreadable.

If you’re not confident eyeballing it just yet, use the plate test. Take your little plate out of the freezer and drip a little bit of the hot fruit onto it. Wait a few seconds. If the dollop sticks—if it doesn’t run right off the plate when you tip it—your preserves are ready.

Ladle the hot fruit into the hot jars, leaving 1/4-inch headspace. Repeat the whole process with the remaining fruit mixture.

Fasten the lids and either:

  • Let cool completely, then refrigerate and use within a month or so, or
  • Make them shelf-stable by processing in a boiling-water bath for 15 minutes. If you’re new to canning, check out the Ball Company’s online guides or Marisa McLellan’s wonderful blog (and book), Food in Jars.
A Toast
See that little bit left in the jar? Add vinegar, oil, parsley, salt and pepper. Give it a shake, and BOOM: blueberry vinaigrette.

Perfect on toast, alongside cheese—or, dad-style, spread on a grilled cheese—this stuff is also a great excuse to whip up vanilla muffins.

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