How to Make Caramelized Onions

Everything you need to know about making perfect caramelized onions, from cutting, peeling, and cooking is right here.

Perfect caramelized onions are easy to make when you follow a few simple rules.

The first thing you need to know is that there is a huge difference between caramelized onions, fried onions, and sautéed onions.

Sautéed onions are what you find on Philly Cheesesteaks and sometimes they are served with fajitas. Sauteed onions will not be anywhere near as sweet and will have more onion flavor.

If you want super dark kind of crispy onions, this is not the route you are looking for.  You want fried onions. 

Fried onions are generally sliced super thin and deep-fried or skillet cooked quickly over super-high heat.  I am not talking about onion rings that are battered and deep-fried.

Low heat and slow cooking are the only way you are ever going to achieve deep brown sweet and savory caramelized onions.  There are no shortcuts.

If you do this the right way, low and slow, there is no need for adding sugar.  There is more than enough sugar in onions if you slow cook them.

Choosing Onions

White onions, yellow onions, red onions, Spanish onions, and Vidalia onions are all great choices for caramelized onions.

I would caution you on the use of red onions. If you are going to use them in French Onion soup, they might make your broth a weird color.

I don’t waste money buying Vidalia onions for this.  Plain yellow or white will work just fine.

How Many Onions

The amount of onions you will need to start with is going to be influenced by how much you need at the end.

I would recommend that you start with at least 2 to 3 large onions so that none of the onions spend too much time on the bottom of the pan during the beginning stages of cooking.

2 extra-large onions will give you about 8 to 10 cups of sliced raw onions that will give you about 1 cup of caramelized onions.

Peel an Onion

I find the easiest method for peeling an onion is to cut it in half from the top to the root end, lay it cut side down, and then cut off the top and bottom.

Now you can get ahold of the skin.

Remove the outer skin.

You also need to remove the super-thin onion layer that is right under the skin.  Large onions tend to have an extra layer that will cook into tough pieces. 

If you have ever eaten an onion ring and the onion was just too tough to eat, it is because someone did not remove that thin layer.

That thin layer is actually trying to turn into a paper skin.

If I am peeling an onion for something that needs rings, like onion rings or placing on burgers, I cut off the top and root end.  Then I use my knife to cut through the skin and at least one layer of the onion.  Then I get my fingers into that cut and pull the cut layers off.

Slicing Onions

Make sure you are in a well-ventilated area.  Slicing a lot of onions in one spot is going to produce a whole lot of sulfur compounds.  There will be tears.

Using a peeled onion, cut the onion in half and lay on cut side down onto a cutting board.

Start slicing the onion from a side, you do not want to slice these into half-moons or rings, these will be too long and appear stringy after cooking.

You are looking for thin slivers of onion pieces about 1/4 of an inch thick.

Slow cooking gives the onions times to break down the sugars without burning them.

Electric Skillet Method

Using an electric skillet is my preferred method. I can set the heat without guessing or adjusting the temperature later.

Set an electric skillet to 200 ⁰F and add the oil and allow the oil to heat up. Side note: if you are going to use these in French onion soup, add a couple of tablespoons of butter.

Once the oil is hot, add the onions, put the lid on the skillet, and walk away for 20 minutes.  I know, the struggle is real, but walk away.

After 20 minutes stir and walk away again for another 20 minutes.

After 40 minutes, some of the onions should begin to lightly brown.

Now crack the lid to allow the steam to start escaping and stir every 10 minutes.  As the liquid begins to evaporate, increase stirring to prevent burning.

Always remember to scrap the bottom of the pan to keep all that sugar from sticking to the bottom and burning.  All that goodness down there will add a nice dark color to your onions too!

I set a timer, otherwise, I am likely to walk away and forget they are cooking.

You really need to stir these regularly to keep them all cooking evenly.

Some electric skillets run hotter than others, so you may need to adjust your temperature up just a tad to keep the onions at a very slow simmer.

Depending on how many onions you have in the skillet, the time to cook will take between 1 1/2 to 2 1/2 hours.

Just remember to keep moving the onions around to encourage even browning.

Stovetop Method

These can be made on a stovetop, but you want to make sure that the heat is never any higher than medium-low.  Use the same method as using an electric skillet, but decrease the time for checking and stirring the onions by half.

This method will take less time but will need to be watched much closer.  There really is a fine line between perfectly cooked and overcooked.

Slow Cooker Method

Mix the onions well with oil before turning on the slow cooker.

Set the slow cooker to high and stir every hour for the first 4 hours, then every half an hour until they are done.

This will take 6 to 8 hours depending on how quickly your crockpot heats up.

Alternatively, you can set the slow cooker to low and stir every 2 to 3 hours.  It will take around 11 hours at low.

I do not like the slow cooker method because the sides of a slow cooker tend to get hot and any onions that are touching the sides tend to burn.

The onions come out more like steamed onions in my opinion.

Color When Done

If you have used the electric skillet or stovetop method, your onions should be dark brown.

When using the slow cooker your onions may never get past a pale brown color before you lose your patience.

The darker the color. The sweeter the onions will be.  Just don’t go so far as to black-brown or they will taste burnt.

Tips for Success

• Low and Slow, do not be tempted to turn up the heat
• Do not add salt
• Do not add sugar
• Follow the suggested times for stirring
• Stir infrequently in the beginning, stir often near the end
• Do not walk away to do something else near the end, you’ll burn the onions you just spent 2 hours making!

Where to Use 

• French Onion Soup – our favorite use
• Hamburgers
• Pizza Topping
• Bratwurst
• Hot Dogs
• Sandwiches
• Flatbread Topping

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