Preserving Onions by Caramelization

We received another large number of Walla Walla sweets this year and are busy trying to find new ways to process them.  One method we learned from a friend from the Walla Walla Gleaners was to caramelize them in a crock pot and freeze them.

To do this just peel, then shred the onions in a food processor.  Fill your crock pot with them to its capacity.  Turn its temperature to low and put the lid on, slightly canted, or with an edge propped up, so some moisture can escape.  We also added a couple pinches of kosher salt to ours, to try to draw out more moisture, but this probably isn’t necessary.

Come back and stir them every few hours.  When you’re gone for the day, or asleep at night, make sure the crock pot is on its lowest setting.  On ours the lowest setting is warm.  This will keep it warm enough to keep bacterial growth at bay, and will continue the caramelization, but should keep it from burning while you can’t stir it.

After several batches, we found that the onions reliably reduced to about one cup for each quart of shredded onion.

The onions are finished when they are a deep brown color, and when they have stopped reducing.  The time will depend on the water and sugar content of the onions, and on the volume and temperature of your crock pot.  In our 5.5 quart crock pot, on the warm setting at night and the low setting during the day, with Walla Walla Sweet onions, an average batch seems to be taking about 30 hours.

When completed, ladle into food storage bags, small canning jars, or other freezer-tight/safe and convenient containers.  I used half-cup and cup measures so I had a couple convenient volumes I could pull out of the freezer to use.

Since we’re still processing these, we haven’t used them much yet.  We suspect their texture will break down to some extent when thawed.  They will probably be best added to soups and stocks or sauces, or anywhere else where the flavor is desirable but their form and texture won’t matter as much.

Best of luck!

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