Crockpot Caramelized Onions

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(Paleo, AIP, GAPS, Wahls)

Crockpot Caramelized Onions | Phoenix Helix

“Banish the onion from the kitchen and the pleasure flies with it. Its presence lends color and enchantment to the most modest dish; its absence reduces the rarest delicacy to hopeless insipidity, and dinner to despair.” ~ Elizabeth Robbins Pennell


If you’ve ever made caramelized onions the traditional way, you know they take almost an hour in a skillet over low heat, stirring occasionally. While this is an opportunity for cooking meditation, it can be challenging for the impatient among us! That’s where this recipe is a godsend. Just pop the onions in your crockpot in the evening and walk away. In the morning, your house will smell amazing and you’ll have enough caramelized onions to store and use at a moment’s notice.


In honor of Dr. Terry Wahls , I love celebrating the nutritional power of vegetables. Look how your body benefits when you incorporate onions into your diet:

  • Prebiotics: You’ve heard of probiotics, but do you know what prebiotics are? Mark Sisson calls them “food for our flora.” They feed the beneficial bacteria in our digestive tract, which is vital to nutritional healing. Onions are a potent prebiotic food.
  • Antioxidants: Onions are high in polyphenols and flavanoids, which are antioxidants that support our health in a myriad of ways. As long as they are cooked over low heat, these nutrients remain in the onion.
  • Detox: Dr. Wahls lists onions under the category of sulfur-rich vegetables, which support our bodies’ natural detoxification pathways, another important component of a healing diet.
  • Research has shown that onions are a potent anti-inflammatory, can increase bone density, and even have cancer-prevention benefits.
  • Vitamins: Onions are also a decent source of Vitamin C, B6, Folate, Potassium and Manganese.
  • Carbs: They are also a good source of carbohydrates, which can come in handy when you’re on a grain-free diet and find yourself accidentally eating too low-carb for your health.
  • Varieties: All onions are good for you, but here’s an important fact: sharp onions have 5 times more antioxidants than sweet onions. They also caramelize better, so choose them for the recipe below.

Recipe: Crockpot Caramelized Onions
adapted from Shockingly Delicious


4 lbs. onions
3 Tbsp. extra-virgin olive oil


  1. Peel onions, slice thinly, and toss in the crockpot.
  2. Drizzle oil over the top. Use two spoons to toss until evenly coated.
  3. Cover and cook on LOW for 12 hours, until onions caramelize. They reduce greatly in size, become a deep brown in color, and develop a sweet and intense flavor. (If you’re using an Instant Pot, choose the Slow Cook “Normal” setting and cook the same amount of time.)
  4. This recipe makes 3 cups. They’ll last in the fridge 1 week or in the freezer 6 months.
  5. Uses: They’re delicious by themselves as a side dish. They also taste great on top of steak or liver. You can add them to an omelet or fritatta, or use them as a topping for a grain-free pizza, sandwich or wrap. Add them on top of a baked sweet potato, or sauté them with any of your favorite vegetables. Anywhere you add them, they’ll bring a rich burst of flavor.

Looking for more slow cooker recipes? Check out my recipe roundup
50 AIP & GAPS Slow Cooker Recipes

50 AIP & GAPS Slow Cooker Recipes

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This post is linked to the following blog carnivals:
Paleo AIP Recipe Roundtable, Whole Food Friday, Simple Meals Friday, Allergy-Friendly Lunchbox, Make Your Own Monday, Natural Living Monday, Fat Tuesday, Healthy Tuesday, Traditional Tuesday, Whole Foods Wednesday, Wildcrafting Wednesday, Gluten-Free Wednesday, Real Food Wednesday, Fresh Foods Wednesday, Allergy-Free Wednesday, Waste Not Want Not Wednesday, Wellness Wednesday, Thank Your Body Thursday, Tasty Traditions, Pennywise Platter, Paleo Rodeo, Simple Lives Thursday,

Crockpot Caramelized Onions | Phoenix Helix
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30 thoughts on “Crockpot Caramelized Onions

  1. Pingback: For the Love of Veggies: Onion Spotlight | Paleo Digest

  2. I just got a large batch of onions in my veggie share this week so I decided to give this a try.
    I was a bit skeptical. Caramelizing onions has always seemed so hard and sort of mysterious — but wow — this totally worked! What a better way to do this! Thanks so much for the great tip.

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  4. These look like something my parents would enjoy. Though they are packed with nutrients, I really can’t bring myself to like onions. :/

    • Don’t feel bad ~ I can’t bring myself to like brussel sprouts (and believe me, I have tried!) We all have different tastes. 🙂

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  7. Hi Eileen,

    I love this! Thank you so much for sharing. I love caramelized onions but often avoid making them because of the vigilance required to do so. I can’t wait to try this. Thanks again!


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  9. I am recovering from surgery; anti-inflammatory is a very good thing for me right now (three weeks out and I still have some swelling and bruising) plus detox (the drugs to knock me out for the required 4 hours is still in my system making me sluggish and knackered).
    I’ll be making this soon. Thank yu

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    • Anything but vidalias/sweet onions. Regular yellow, white and red onions are all considered “sharp” with red being sharpest.

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  15. Thank you for this amazing recipe! I’m going to make some tonight. I fry or saute onions every day in almost every meal and this will help save me a step!! 😀 Thank you thank you thank you.

    p.s.- Can I cook a only 3 cups at the same time, or would they be done in 8 hours instead of 12?

    • Hi Rachel. Since the onions freeze well, I recommend making a full-sized batch. It will save you far more time. The onions shrink a lot when cooking, so it you started with 3 cups raw, it would be a pretty small amount once fully caramelized. I’m not sure if it would reduce cooking time.

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  17. What a unique idea! For GAPS intro, would it be ok to use tallow instead of the olive oil, or would that negatively affect the outcome? Thank you so much!

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