Low & Slow Caramelized Onions: Easy Flavor Boost

When onions are first caramelized, they are such a delicious way to add flavor to meats, dips, breads, omelets, pastas, mashed potatoes, rice, homemade pizza–on and on we can go! Whatever savory or veggie dish you like–and they’re so easy to make too! Here’s how you do it…


1/4 cup unsalted butter
6 large onions
2 tsp brown or white sugar (optional)
Kosher salt (to taste)
pepper (to taste)


  • Peel and slice onions into rings about 1/4″ thick. You can cut in half first if you prefer strands rather than rings.
  • Melt butter in a large, heavy saute pan over medium to high heat. Cast iron is ideal for this job, but stainless steel will do the trick too.
  • Once the butter has melted, toss the slices into the hot pan and stir to coat them well. Cook for 5 minutes at this temperature, stirring frequently.
  • Reduce heat to medium. Cook for 15 minutes, pushing them around frequently with a wooden spoon (scraping up bits) so they don’t burn.
  • After 15 minutes, sprinkle sugar over top and stir to coat (optional).
  • Reduce the heat to medium-low and remove once they are golden brown and caramelized. The entire process can be a total of 45 minutes to an hour depending on how thick you’ve sliced them. Season with salt and pepper near the end.

Did you catch the heating process? Start medium/high then go low in stages. There’s no need to rush things along, let the flavors develop. It can take up to an hour to get things “just right”.

Some Tips

  • You can make big batches and refrigerate to use during the week, they keep well in an airtight container. Yes, they can be frozen for future use too!
  • You don’t need a strict recipe, start with 1 tablespoon of fat (or olive oil) per 2 medium size onions and then add whatever seasonings you wish.
  • Trying adding herbs such as dried thyme for a tasty twist (add the last 15 minutes or so).
  • You can add some olive oil at the start (along with the butter) to increase the smoke point.
  • If you’re looking for a “jam” consistency, try adding about 1/4 tsp of baking soda per 2 medium onions (do this right at the beginning).
  • Once they are done, make a scrumptious spread by pureeing them in a food processor, delicious!
  • Adding sugar isn’t absolutely necessary since they will produce their own sugar as they are heated and caramelize.
  • For best results use a sweet variety like Vadalia, Walla Walla and Sweet Imperial…but you can also try red or regular cooking varieties.
  • You can slice them as thick or thin as you like, but the finishing time will need to be adjusted.
  • If you find the bottom of the pan is burning before things are just right, deglaze with chicken stock or a bit of water, making sure to scrape up the bits with a wooden spoon.
  • Use a large pan for more surface area, this will help speed things along.
  • For extra flavor, try adding a good splash of balsamic vinegar the last 10 minutes before they’re done.
  • Keep the pan uncovered the whole time, you are trying to draw the water out of them…not steam them.
  • To cut down on fat, use canola or olive oil–or use a mix (about 2 parts butter to 1 part oil).
  • Why is it that they taste so darn good? It’s all about concentration of flavor. The long cooking process breaks down the onions & releases the water which then enhances the flavor.

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    • Lindy

    Make sure not to use a not-stick or teflon pan! The onions will never carmelize if you do. I learned this the very hard way!

    • Iain

    Using oil will not cut down on fat–it’s 100% fat. It will just use a different kind of fat that’s healthier.

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