What is the best method for slow cooker caramelized onions?

January 14, 2013 2:29 PM

What is the best method for slow cooker caramelized onions? I've been meaning to make a nice big batch but googling around gives me a very wide variety of methods. High or low. Six hours or twelve. Lid on or lid off, or lid on and then off or off and then on. Give me your tried and true method.
posted by Drinky Die to food & drink (11 answers total)

My method is uber simple. I put a half pound of butter in the bottom of the crock pot. I thinly slice enough onions to fill the crock pot. I take several sprigs of thyme and tie them up with string and tuck that into the onions. a few heaping pinches of salt go on top. Then low for the max time setting. I start them covered, but once the onions have started to express their liquid I uncover them for the rest of the time period. If they start to dry out I'll add some water, of if I have a bottle hanging around some sherry.
posted by JPD at 2:33 PM on January 14

that said I'm not sure you could screw this up short of something silly like not using any fat.
posted by JPD at 2:34 PM on January 14

that said I'm not sure you could screw this up short of something silly like not using any fat.

I screwed it up, but I'm not sure how (so will be watching this thread with interest). The one time I did it -- and I think I took the slooooooow route -- I ended up with onions poaching in two to three times their volume in liquid. Don't remember if I used oil or butter (most likely butter), but even after cooking for 24+ hours, all I ended up with was onion mush.

Save me too, AskMe.
posted by mudpuppie at 2:44 PM on January 14

the older the onions the less chance of it turning to mush (according to Mts Kairab who grows her own). She tells me she only slow cooks the December-January ones (harvested in August -september) because they're slightly dehydrated and so will absorb, rather than throwing off liquid like very fresh onions.
posted by kairab at 2:50 PM on January 14

I also find brown onions the best for caramelizing as they don't seem to turn to mush as easily as the sweet ones and they sweeten up with slow cooking.

If they start to go mushy or don't caramelize just right, drain off the butter add some balsamic vinegar and brown sugar and herbs, to taste cook it a bit longer and call it onion jam or at least that's what I did.
posted by wwax at 3:01 PM on January 14

Didn't we beanplate this after the you-need-30-minutes kerfuffle last year?

Yep. Lotta discussion & recipes here. The takeaway lesson seemed to be "leave the lid off" to keep them from getting mushy.
posted by phearlez at 3:35 PM on January 14

Low heat, lid off. Here's the secret: a pinch (an actual pinch) of baking soda. It facilitates the reaction you're looking for, but you definitely don't want to taste baking soda in your onions. You can do it without the soda, but if you do use soda you can get MEGA CARAMELIZED onions. Add a little sugar if you wanna go nuts.

I like to julienne a few jalapenos and let it go until it's super concentrated and a little like fruit roll-up texture but not broken down and put it on anything you might ever consider eating.
posted by cmoj at 3:49 PM on January 14 [4 favorites]

I saw this episode for slow cooker onion soup on Cook's Country.

The recipe starts with creating a slow cooker onion "base" that you then add broths to. It look pretty genuis to me, and I've been contemplating the making base, freezing it, and then using as a starter for quick and easy french onion soup. But I could see it being used for all sorts of oniony pleasures.
posted by helmutdog at 9:56 PM on January 14 [1 favorite]

Question about the lid: Keeping the lid entirely off seems like it would let out too much heat. Can you just keep the lid somewhat ajar?
posted by marsha56 at 9:02 PM on January 15

sure, but its more important you get evaporation to avoid mush.

Baking soda will increase the browning but also increase the chance of mush.
posted by JPD at 8:15 AM on January 16

Caramelized onion FPP
posted by the man of twists and turns at 8:51 PM on March 30