The BEST Dehydrated Caramelized Onions

~With steps to Caramelize Onions Easily in a Slow Cooker~

Caramelizing onions is a wonderful way to pull flavor out of the simplest of ingredients and they are good on pretty much everything. The only problem is that they are surprisingly tricky to make. They take time to slowly brown and caramelize, usually about 45 minutes on the stovetop. It’s easy to burn them and it’s easy to remove them from the stove before they’re actually done.

Caramelizing onions, by slowly cooking them in a little olive oil and butter until they are richly browned, is the traditional method. But for dehydrating, this is problematic because fats and oils do not dehydrate well and will turn rancid in storage.

So what’s a Foodie-loving person to do for long-term storage of these onions? I have come up with a solution. This is an easy, reliable method to make your own “roasted” onions without all the work and constant attention you would normally have to deal with when caramelizing onions. And because it uses no fats or oils, you can safely dehydrate and store them as well.

6-22-2016 Update
Note: I have a 6-quart (5.7 liter) slow cooker that I use mostly for this recipe and can easily fit 3 pounds (1.4 kg) of onions into it. That’s about 8-9 large onions.

Caramelizing Onions in Crock Pot

Slow Cooker Collage

  1. Thinly sliced onions will burn faster and stick to the bottom of your pan. Aim to slice your onions 1/4 inch thick—their heft will prevent them from drying out.
  2. Pour enough water in the slow cooker just to cover the bottom.
  3. Turn heat to high and wait for water to boil.
  4. Slice onions finely while waiting for water to boil.
  5. Once water is boiling, add sliced onion. You are not sautéing your onions—you are trying to slowly coax flavor out of them. It takes time for the onions’ sugars to caramelize.
  6. The slow cooker should stay at the constant temperature of the HIGH setting for the entire process. Tightly lid the slow cooker and allow it to do its job.
  7. Stir the onions occasionally and let it cook until softened. Add a splash more water if they seem dry.
  8. After 4-6 hours, you will notice a light browning effect happening with your onions. At this point, leave the lid ajar so the liquid can evaporate.
  9. When done, the onions should look brown and delicious (see notes). Depending on the size and model of your slow cooker, these usually take anywhere from 8 to 12 hours to fully caramelize to a deep golden brown.


Per suggestions from one of my groups, I tried making a few batches adding a splash of balsamic vinegar to one pot and a splash of white wine to another. This amplifies the sweetness and just makes them taste amazing. Totally optional though.

Onion Colors Collage

It is your choice as to how long you wish to slow cook your onions. I have stopped the process at various stages and ALL of them have been delicious.

  • Blonde Onions: Ideal for French soup, these cappuccino-colored onions should still have a bit of bite.
  • Golden Brown: Go a stretch longer to get them a little more caramel-colored; great for onion jam.
  • Deep Golden Brown: This tangle of these nearly crisped onions gives you the BEST burger topping and snacking food. This is a personal favorite here at Casa Colleen.

It’s almost impossible to overcook these onions, but I’ve found that 8-10 hours makes soft, richly browned onions that still have a bit of bite. Remember, caramelization takes time. Don’t take them off too early. They are the best when they are a rich brown color, much reduced from where you started.

If you do not wish to dehydrate your onions, you are pretty much done. These are perfect for soups and topping sandwiches. For jammier, softer, even more deeply caramelized onions, you can continue cooking for another few hours if you wish.

Any liquid remaining after cooking is fantastic added your next soup or rice, or risotto. There’s flavor in the bottom of the pan, too. Take full advantage of the brown bits and deglaze with stock, wine, beer, vinegar, or even water. (You can stir to incorporate with the onions if you do not wish to dehydrate them, and they’ll absorb all that flavorful liquid, making them taste even better.)

Dehydrating Caramelized Onions

  1. Turn on your food dehydrator and set the temperature to 135°F/57°C. Allow it to preheat for a minimum of 15 minutes.
  2. Arrange onions in a single layer using a solid sheet or parchment on your food dehydrator trays. Try to make sure they don’t overlap.
  3. Dehydrated onions should be crispy when fully dried. Rotate your trays for even drying if needed.
  4. Approximate drying time will be anywhere between 4-12 hours depending on conditions and how caramelized your onions are.

Onions DHed Collage

©2016 21st Century Simple Living

10 thoughts on “The BEST Dehydrated Caramelized Onions

  1. Deb says:

    Have you ever tried them on the low setting?

    1. Admin says:

      The low setting of the slow cooker or the dehydrator?

  2. Jamie Marie says:

    sounds yummy, thanks for sharing at the homesteader hop!

    1. Admin says:

      Thanks for having me Jamie Marie !!!

  3. Nadine Frandsen says:

    I have dehydrated yellow and purple onions, both raw and diced. Green onions sliced. Also, yellow rings cut thicker and blanched first- Yumm!! I have learned that DH onions are great for adding to any recipe and wonderful for snacking on and as salad toppers. I’m thinking about making my own onion powder next- yellow onions I would guess….
    I do have a question, though- I am interested in making french onion soup for my Hubby- he LOOOVES french onion soup!! Is there a recipe somewhere that I can follow?

    1. Admin says:

      I will put French Onion Soup on my list of recipes to write about. These onions are great in it and make it easy to whip up fast !!!

  4. Annie says:

    Thank you for this recipe 🙂

    I would like to give it a go and was wondering
    how many onions did you do in the slow cooker at the one time?


    1. Admin says:

      I have a 6 quart slow cooker that I use mostly for this recipe and can easily fit 3 pounds (1.4 kg) of onions into it. That’s about 8-9 large onions.

  5. Sandy D. says:

    I wonder if I added in some sliced peppers, it if would rehydrate well for peppers and onions topping for sausage? Also, I add a little sugar to my onions early in the process, then add balsamic right at the end. I wonder if the sugar would work here as well? I see my next experiment developing..

    1. Admin says:

      That sounds wonderful !!! Please let us know how it turns out !!!

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