Strawberry Rhubarb & Caramelized Onion Jam

allium canning
too many good recipes
strawberry rhubarb it is

It’s a poetry jam, man.

Today’s haiku is brought to you by the letter “A.” A is for allium and I can’t seem to stop Can Jammin’ the magical allium family: shallots, garlic and Cippolini onions (oh my!).  I know Spring is not quite here yet, despite the post-Flood sunshine and 60 degree temps today, and it is cruel of me to tease you with thoughts of strawberry & rhubarb when we’ve got a ways to go until those gems start popping up at local markets.  But I had both strawberries and rhubarb in the freezer from last June (have I mentioned how much I <heart> my chest freezer?) and a recipe for strawberry, rhubarb and caramelized onion preserves that I was just itching to try.  A pile of onions from last week’s farmer’s market were waiting for some Can-Jammin’ action.  It was a match made in heaven.

This recipe had some odd quirks, like strangely short cooking times, a longer processsing time, an aggressive set and a yield that was well off the estimate (see details in Options below), but the end result is delicious.  The caramelized onion gives the strawberry jam a depth of flavor that must be tasted to be believed; I can tell that the onion is there, but if I didn’t know the recipe I would not guess, I would simply ask “how did you make this?!”  The jam is not too sweet, despite containing more sugar than I would normally use, nor too tart, despite a half cup of lemon juice. It is, in a word, fabulous. If I can stop eating it by the spoonful, I’m guessing it would be equally good on meats & cheeses as on toast or muffins.  Another allium winner!

For more strawberry rhubarb lovin’, see Strawberry Rhubarb Jam, Two Ways, Strawberry Rhubarb Preserves, Strawberry Rhubarb Amaretto Sauce, or Rhubarb Strawberry Crumble.

Adapted from Strawberry, Rhubarb and Caramelized Onion Preserves in Homegrown Pure and Simple by Michel Nischan


Strawberry Rhubarb & Caramelized Onion Jam


  • 4 or 5 small Cippolini onions (about 1 cup or 3 and 1/2 oz), thinly sliced (or other yellow or white onion)
  • 1 heaping cup rhubarb, washed well, trimmed and cut to 1/2-inch slices (fresh or frozen)
  • 2 tsp grapeseed or canola oil, divided
  • 2 tsp local honey
  • 1/2 cup lemon juice (fresh or bottled, or a combination)
  • 2 and 1/2 cups sugar (I used a mix of turbinado and evaporated cane juice)
  • 3 cups hulled, halved strawberries (fresh or frozen)
  • zest of 1 lemon
  • 1/4 tsp each of salt and freshly ground black pepper, or to taste (optional)


  1. If canning, prepare canner, jars and lids.
  2. Heat a medium stockpot or Dutch oven until hot.  Add 1 tsp oil and onions; toss well to coat onions in oil.  Sauté over medium to medium-low heat, stirring frequently, until softened and beginning to brown, about 5 minutes (if onions begin to stick, add a tiny amount of white wine and scrape the bottom of the pan to get up all the good stuff). Toss rhubarb pieces in remaining 1 tsp of oil and add to pot. Sauté for 1 – 3 minutes until rhubarb looks moist (frozen rhubarb will ‘moisten’ more quickly). Add honey, then raise heat to medium-high and cook, stirring constantly, until the onions are brown and the rhubarb is beginning to break down, about 6 – 10 minutes.

  1. Add lemon juice and sugar, raise heat, and bring to a boil. Add strawberries (with juice, if frozen and thawed) and bring to a boil.  Reduce heat to a lively simmer, stirring frequently to prevent scorching, until liquid has thickened and darkened, about 15 – 20 minutes (mine read 216 – 218 degrees F on an instant thermometer when I stopped cooking; typically 220 degrees F is the gel point). Add lemon zest, salt & pepper (if using). Stir well, taste, and adjust seasonings if necessary.
  2. Fill hot, sterilized jars to 1/2-inch headspace and process for 20 minutes in a boiling water bath, or store refrigerated in a clean glass jar.

Yields about 4 cups.


  1. A few things confuse me about the original recipe.  One is the cooking times: the original states to sauté the onions for 1 to 2 minutes, then add rhubarb (3 minutes), then sauté over medium-high heat for 6 minutes.  I don’t know about you, but rarely have I seen a cup of onions caramelize in 10 minutes of cooking.  I increased the cooking time for the onions alone and the onion/rhubarb mix, to nicely brown the onions.  Secondly, in Nischan’s recipe the strawberries are not brought to a boil after adding, in fact, he lowers the heat, then simmers for 5 minutes.  At 5 minutes of cooking, my mixture was very watery and at a temp of 214 degrees F (the extra liquid could be related to my use of frozen strawberries, but – fresh strawberries would release juice too). With no added pectin, and little natural pectin, I figured it would need extra cooking time to develop a jammy texture. I continued to cook the preserves for 20 minutes, raising the heat and stirring frequently, but never got to the gel point (220 degrees F); eventually I gave up on it (at about 216 – 218 degrees F) and decided, if it stayed strawberry sauce, so be it.  Ironically the resulting jam, once cooled, has almost too hard a set; it’s still spreadable, but just barely.  So either my thermometer is way off (I tested it in some boiling water and it read 211.5 degrees F) or this is a strange recipe. You may want to stay to the shorter end (15 minutes) of cooking in order to achieve a looser set.
  2. Regardless, the jam is quite delicious. The salt & pepper are optional because I forgot to add them, but I encourage you to try it; I often do this in sweet or savory jams and the tiniest bit can make all the difference.
  3. Do not increase the amount onions or oil, nor decrease the acidic ingredients (strawberries, rhubarb and lemon juice) or you will affect the safety of the canned recipe. If you want to alter these ratios, store the preserve refrigerated instead.
  4. The recipe stated to process in a boiling water bath for 20 minutes.  Jams and preserves are usually processed for 10 to 15 minutes; I’m not sure why this recipe stated 20 minutes, but perhaps it is extra caution because of the onions.  Nevertheless, can’t hurt to follow the recipe and go the full 20 minutes.
  5. The stated recipe yield was 3 pints; I suspect my yield was lower due to the longer cooking time of the berries.


Canned, in a cool, dark spot for up to 1 year.  Refrigerated for up to 2 months.


Spring, or year round with frozen fruit.


  1. I would have never thought of the combination of strawberries and alliums – this sounds really interesting. I might try this recipe when strawberries are in season here.

  2. That sounds amazing! and i love the color – its like essence of spring in a jar. which i guess means you captured spring in your chest freezer — and i am so wishing i had one!!

  3. local kitchen

    This one is pretty delectable, I have to say. I probably cooked it for too long, so the texture of Nischan’s original is likely much different, but the flavor is sooooooo good.

    And yes, I LOVE my chest freezer. While there are some things I miss about my many, many years of living in tiny apartments in the City, one of the things I love about the ‘boonies’ is our garage. 🙂

  4. This is so gorgeous. I want it. My rhubarb is just now poking its little heads out. The strawberry plants are green. But it’s still a long way off. Maybe you should do a giveaway? (smirk!) I find it amazing that it set so hard! Wha’ happen? The amount of lemon?

  5. local kitchen

    Ha! Tai would kill me. I gave away a jar this morning to a friend who stopped by, for an impromptu Thursday morning tea break (such are the things you can do when you work from home) and he gave me such an evil scowl.

    I have no idea why it set so hard; granted, I didn’t actually follow the recipe (but when do I ever?); it could be all the lemon juice. Could be that it would have set normally if I only cooked it for 5 minutes, but it sure didn’t look like it, and if so, I would have to guess my thermometer is way off. Need to Google how to re-calibrate it…

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  13. Lorri

    This is amazing jam! I made this for an outdoor wedding that we had loaded (jalapeno, green onion and bacon) corn muffins with the meal and they were amazing together!

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