Crockpot Caramelized Onions

We like caramelized onions…very handy to have in the freezer, ready to use.  Slow cooking is certainly the easiest way to prepare them, if you can stand all that delicious smell all day!  I bought a $13 “original” 4 quart crock pot around the holidays last year, and tried it out with this recipe.  
I froze mine in quart freezer bags, kind of dividing them into two sections in the bag, then folding the bag before freezing so I could easily remove half a bag if needed. 
This means I can use up  a sale bag of onions, or another way to use onions from the garden without wasting them.
Use them as garnishes for soups, sandwiches, dips, meats, and vegetables.                    
                  Caramelized Onions in the Slow Cooker
  3             pounds  yellow onions (4 to 5 large onions) -- (3 to 5)
  3             tablespoons  extra-virgin olive oil or melted butter
     1/2      teaspoon  salt
  3              tablespoons sherry (or balsamic or red wine vinegar)
  4             quart  to 6-quart slow cooker (spritz with cooking spray or oil the sides and bottom of the crock)
Thinly slice all the onions: Peel and thinly slice all of the onions into half-moons. Transfer all the onions to the slow cooker - the slow cooker should be half to three-quarters full.
Toss onions with the olive oil: Drizzle the olive oil or melted butter and the salt, if using, over the top of the onions. Toss to evenly coat all the onions with a thin glaze of oil.
Cook for 10 hours on LOW: Cover the slow cooker and cook for 10 hours on LOW. If you're around while the onions are cooking, stir them occasionally - this will help them cook more evenly, but isn't strictly necessary.
After 5 hours, I poured 3 tablespoons of sherry over the onions, stirred them and continued cooking.
After 10 hours, the onions will be golden-brown and soft, and they will have released a lot of liquid. If you like them as they are now, stop cooking and pack them up.  If not, leave the lid ajar and continue cooking another hour or 2 for thicker onions.
Refrigerate or freeze the onions: Remove the onions with a slotted spoon and transfer them to refrigerator or freezer containers. If any liquid remains in the slow cooker, transfer the liquid to a separate container - this can be used as cooking broth in another recipe. Onions will keep in the refrigerator for one week or in the freezer for at least 3 months.


  1. Thanks for sharing this. Just picked up 25 pounds of red onions and want to be sure none go to waste if we don't get them all used fast enough.

  2. What a great recipe! Can't wait to try it out--thanks, Sue! :^) :^) ;^)

  3. Could these be canned?

    1. I would freeze them...there are canning recipes, and I have tried one in the past that had much more vinegar than this one, but they may be problematic.
      The Cooperative Extension says:
      "Neither USDA nor Ball have any current formulations for canning onions in a fat -which is what both butter and olive oil are. Fat does not absorb heat evenly - you certainly have noticed this in cooking where one area of a pan with melted butter begins to darken before other areas do. This uneven heat absorption creates problems in canning. Also, fat coats other foods - in this case the onions -so that food do not absorb heat evenly either. Based on the info from USDA, please feel free to continue creating the caramelized onions as mentioned in the first half of the recipe, but for safety's sake move the onions to a freezer for the second half of the recipe."


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