Sweet, jammy, and no skillet required—slow cooker caramelized onions are my new favorite kitchen hack, perfect for vegan burgers, soup, pasta, & more!
Why You’ll Love This Recipe
It’s genius! No, but seriously – I LOVE caramelized onions, but a lack of patience (guilty!) makes the low-and-slow, constant monitoring, frequent stirring stovetop version less than ideal on a regular basis. This slow cooker caramelized onions recipe, however, is as easy as it gets and great for making a gigantic batch of perfectly caramelized onions to save in the fridge/freezer.
In just 3 steps, ‘set it and forget it’ style caramelized onions in a crock pot end up perfectly rich, deep, sweet and savory, golden-brown caramelized onions. It’s given me the perfect excuse to turn these into a kitchen staple I can’t be without - perfect for pasta, vegan burgers, flatbread mini pizzas, my vegan French onion soup, and more.
Looking for more easy vegan side dishes? Try out these brown sugar green beans, crispy roasted sweet potato wedges, air fryer asparagus, or air fryer butternut squash.
The Ingredients
Refer to the recipe card for the full list of ingredients, substitutes, and quantities.
The Best Onion For Caramelizing
Any variety of onions will work. While Vidalia and Walla Walla onions are naturally sweetest (and won’t need added sugar), caramelized red onions, yellow onions, or white onions also work, each providing a slightly different flavor.
Recipe Variations
- Vegan butter: For 'buttery' flavor, make vegan butter to caramelize onions instead of using oil.
- Balsamic caramelized onions: 1-2 teaspoons of balsamic vinegar adds rich, bright depth. Red wine vinegar also works.
- Fresh thyme: Perfect if you’re making caramelized onions for soup!
How to Make Caramelized Onions in A Slow Cooker
Step 1: First, peel and thinly slice the onion.
Step 2: Stir the onions, oil, salt, and brown sugar (if using) in a crock pot. Cover and cook on LOW for 10-12 hours, stirring 1-2 times if required.
Time-saving tip: Use a mandoline or food processor slicing disk to prep the onions in no time. Just don’t slice them too thin, or they’re more likely to burn.
For more deeply caramelized, jammier crockpot caramelized onions, continue to cook for 3-5 hours with the lid slightly ajar (to evaporate the liquid).
Recipe Pro Tips
- Cut even-sized pieces: For uniform cooking.
- Monitor and adjust: Your slow cooker may run a little warmer than mine, so it’s a good idea to monitor it your first time trying the recipe – occasional stirring might work best for you.
- Jammier onions: After 10 hours, stir, place the lid slightly ajar, and cook for another 4-5 hours for sweeter, deeper, more complex onions.
- Save the juice: If you don’t cook off extra juices, drain it, freeze it in an ice cube tray, and add to stocks, soups, stews, and sauces for depth.
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FAQs
Low and slow works best. However, you’d probably be able to start the process on HIGH for 2-3 hours, stirring occasionally and adding a little more water to avoid burn. Then, finish on LOW for 4-6 hours. Just note this isn’t something I’ve tested, so let me know if you try.
Not at all – especially if you use sweet onions, like Walla Walla or Vidalia onions. Honestly, it comes down to personal preference, especially if you love the depth of brown sugar caramelized onions.
Serving Suggestions
Making crock-pot caramelized onions in bulk is practically a must when you can add them to practically any meal, like:
- In vegan burgers/hot dogs
- Vegan sausages, Instant Pot garlic mashed potatoes, and vegan gravy
- Pasta/gnocchi - easy vegan carbonara, vegan white lasagna, or vegan baked ziti
- In a vegan Just Egg frittata, easy vegan Just Egg quiche, vegan Just Egg omelette, or tofu scramble
- For vegan French onion soup
- Over this easy garlic herb focaccia, flatbreads, and vegan pizza - even vegan breakfast pizzas
- Vegan grilled cheese and other wraps/sandwiches
- In dips (like hummus) and sauces
- Beyond Meat meatloaf and meatballs like this chili sauce and grape jelly meatballs recipe
- Gratins and potatoes dauphinoise
Storage Instructions
Let the slow cooker caramelized onions cool, then store them in an airtight container in the refrigerator for 5-7 days.
Can You Freeze Caramelized Onions
Sure! Caramelized onions freeze very well. Transfer them to a freezer-safe container/Ziplock/Stasher or in smaller portions in a silicone muffin/ice cube tray, and store for up to 3 months.
Then, thaw in the refrigerator overnight before using or reheating.
The BEST Slow Cooker Caramelized Onions
Ingredients
- 8 yellow onions thinly sliced
- ¼ cup of canola or other neutral-flavored oil
- 1 teaspoon of salt
- ½ teaspoon of brown sugar (optional)
Instructions
- Combine the onions, oil, salt, and brown sugar (if using) in a slow cooker. Mix thoroughly.
- Cover and cook on low for 10 hours.
Notes
- Cut even-sized pieces: For uniform cooking.
- Monitor and adjust: Your slow cooker may run a little warmer than mine, so it’s a good idea to monitor it your first time trying the recipe – occasional stirring might work best for you.
- Jammier onions: After 10 hours, stir, place the lid slightly ajar, and cook for another 4-5 hours for sweeter, deeper, more complex onions.
- Save the juice: If you don’t cook off extra juices, drain it, freeze it in an ice cube tray, and add to stocks, soups, stews, and sauces for depth.
Andrea says
So easy to make these caramelized onions! Love it!