This Caramelized Onions and Mushrooms recipe is an easy way to add deeply savory, sweet, rich flavor to everything from burgers to soups to breakfast dishes. The key is patience and a bit of olive oil for a delicious, soft, craveable result.
Why You'll Love This Dish
It's so delicious. Plain and simple, this is one of those condiments that is completely worth the time it takes to make. It's incredibly savory, sweet, and adds a wonderful depth of flavor to any dish.
It's versatile. Try these caramelized onions and mushrooms in everything from burgers to breakfast! You can add them to soups, stews, sauces, stir-fry dishes, salads, omelets, quiche, or sandwiches. I've even put them in quesadillas!
While the onions may take time to brown, this dish is really easy! It's a simple recipe. All you have to have is a bit of patience and stir every 5 to 10 minutes for a perfect result every time.
You can make it in advance. Spend some time making these caramelized onions and mushrooms and you'll have this delicious condiment to add to everything you eat for a week.
What You'll Need
- Onions I used yellow onions here, but you can use red onions or sweet onions too.
- Mushrooms Cremini mushrooms are my choice, but baby bella or button mushrooms (white mushrooms) will work just fine.
- Garlic Fresh garlic is always my choice when available, but you can try using chopped, jarred garlic as well.
- Extra Virgin Olive Oil A good quality oil would be nice here because you can taste it so clearly, but use whatever you have on hand.
- Thyme Feel free to use dried or fresh thyme here. You can omit this if you don't have it on hand or don't like it.
- Salt Diamond Crystal Kosher Salt is my brand of choice. It coats food evenly and is less salty than traditional table salt by volume, making it much easier to taste as you go! You can use salt and pepper if you'd like.
How to Make Caramelized Onions and Mushrooms
Step One Set a cast iron or stainless steel pan on high heat. Clean the mushrooms by wiping them with a clean cloth or paper towel. Cut off the bottom eighth inch of the mushroom.
Slice and add the mushrooms to the pan, cooking until golden brown on both sides.
Step Two Slice or finely chop the garlic.
Step Three Thinly slice your onion.
Step Four Add the garlic, onions, thyme, and salt along with a bit more olive oil to the pan. Mix the cooked mushrooms in with the remaining ingredients. Turn heat to medium-low.
Step Five Stir every 5 or so minutes, ensuring the onions don't burn. If everything appears dry, add a bit more oil. This process will take about 45 minutes to an hour. See below for the stages of cooking. You're looking for a deeply browned end result without any burning.
Be patient - the caramelization process can take a while when done properly!
Step Six When the onions are browned and fully softened, almost disintegrating into one another, remove them from the heat. Serve right away or store in the refrigerator for future use.
Mushrooms won't brown at low heat, and sauteed onions will burn at high heat, so cook your mushrooms first. This will allow them time on high heat to develop a browned exterior before adding the onions at a lower heat.
Olive oil is best here because the overall taste is preferable. If you are out of olive oil, try a neutral oil like grapeseed or avocado oil. Some recipes recommend vegetable oil, but I personally do not like the taste it imparts.
In this particular recipe, I call for olive oil because of the higher temperature used for the mushrooms. This could negatively affect the taste of the butter. If you are not using mushrooms, feel free to try this recipe with butter.
Absolutely! As this recipe proves, the two are a great pair when sauteed together. I do recommend starting the mushrooms first, however, as mushrooms do well with an initial sear on high heat.
Yes, but not frequently. Stirring every 5 to 10 minutes is plenty to ensure nothing is sticking or burning.
No Mushrooms Feel free to make this recipe with just onions. It will take less time and still be quite delicious.
Different Herbs You can omit the thyme, or garnish at the end of cooking with a fresh, soft herb like parsley.
Sautéed If you are running short on time, you can stop cooking once the onions are just softened for a less sweet and concentrated sautéed onion. You can also make sautéed mushrooms on their own, which I do often.
How to Store
Fridge Leftover cooked onions and mushrooms can be stored in an airtight container for 5 to 7 days in the fridge. To reheat, add directly to the dish you are making (if it's a soup, stew, or sauce), or reheat in a pan over medium-low heat.
You can also reheat them in the microwave for a few minutes.
Freezer You can freeze caramelized onions for up to 3 months. I recommend placing them in a gallon storage bag and squeezing out all of the air before freezing.
When you want to add some onions to your meal, break off a piece and add it directly to the pot. You can also defrost in the refrigerator overnight and then reheat on the stove or in the microwave as above.
The texture of the mushrooms may suffer when freezing, so I recommend making a batch of just onions if you are freezing. However, if the texture doesn't bother you, go for it!
How to Serve
Below are some ideas for ways to incorporate this wonderful condiment into dishes:
Soup Try stirring some of these caramelized onions and mushrooms into a soup of your choice for a burst of flavor. It would be wonderful mixed into this Greek Chickpea Soup or this Instant Pot Navy Bean Soup.
Roasted Vegetables This is spectacular mixed into roasted vegetables. Try with this Roasted Tenderstem Broccoli or these Roasted Cherry Tomatoes on the Vine.
Roasted Meats Serve this as a condiment for any roast meat of your choosing, such as this roast chicken.
Grain Bowls In place of cucumbers, try some caramelized onions and mushrooms in this Mediterranean Grain Bowls recipe or this Warm Grain Bowl with Goat Cheese and Greens.
Quesadilla Try adding a spoonful to your favorite quesadilla, like this Carne Asada Quesadilla with Ranchera Meat.
Steak, Burgers, Pork Caramelized mushrooms and onions are a perfect topping or side dish for steaks and burgers. Try it on this amazing BBQ Pork Steak from our friends at Girl Carnivore!
Eggs Add a dollop to your favorite egg dish, like this Leek & Squash Quiche.
Potatoes Mix some into your favorite potato dish, like these Calabrian Potatoes or these Air Fryer Fingerling Potatoes.
Bread or Toast Spread onto your favorite toast, bread, or crackers.
Cheese or Charcuterie Board This would be wonderful on a board with cheese, crackers, and meats. Serve with some roasted cherry tomatoes on the vine!
- Be super patient. Properly caramelized onions take a long time, but they are so worth it! Keep your heat on medium-low at the highest, and find something else to occupy yourself. I set a recurring 5- or 10-minute timer so I'm reminded to stir.
- Never use non-stick pans on high heat. If you only have non-stick pans, stick with medium heat for your mushrooms. Cooking on a lower heat preserves the non-stick coating your pans, making them last longer!
- Be sure your pan is hot enough. If you are using stainless steel, check out this cool test (well, cool if you're a food nerd like me) to be sure your pan is hot enough before adding the oil and mushrooms.
- Remove the green stem from the garlic. Do you ever have garlic that tastes a little bitter? Try removing the inner green stem if it is noticeable to decrease this bitterness. See below for the stem I'm referring to.
More Recipes You'll Love
Looking for more flavor-boosting recipes? Try the suggestions below!
Caramelized Onions and Mushrooms
- 1 Large Frying Pan cast iron or stainless steel is preferable
- ¼ cup olive oil extra virgin, divided
- 2 pounds onions yellow, red, or sweet
- 1 pound mushrooms cremini or button
- 2 to 4 cloves garlic optional
- ½ tablespoon thyme leaves fresh or dried, optional
- kosher salt to taste
- Clean and slice the mushrooms. Slice or finely chop the garlic. Thinly slice the onions.
- Set a cast iron or stainless steel pan on high heat. Once hot, add half of the olive oil and mushrooms with a pinch of salt.
- Cook for about 15 to 20 minutes, stirring occasionally until the mushrooms have received a hard sear and are browned on both sides. Bring heat down to medium-low.
- Add the onions, garlic, thyme, salt, and remaining olive oil. Stir everything together.
- Stir again every 5 to 10 minutes for approximately 50 minutes, or until the onions are deeply browned, soft, and sweet. Add a bit more oil as needed if the pan looks dry.
- Taste for seasoning and serve.
- Serving sizes and calories are approximate.
- Don't heat the onions above medium-low or you may risk burning them.
- If you only have a non-stick pan, use medium heat for the mushrooms. Using a low heat with non-stick cookware will preserve its coating and make the pan last longer.
- Cooked onions and mushrooms can be stored for 5 to 7 days in the fridge or for 3 months in the freezer.
- I recommend placing them in a gallon storage bag and squeezing out all of the air before freezing.
- The texture of the mushrooms may be altered when frozen and reheated.
- To reheat from the fridge, add directly to the dish you are making (if it's a soup, stew, or sauce), or reheat in a pan over medium-low heat. You can also reheat them in the microwave for a few minutes.
- From frozen, break off a piece and add it directly to the pot. You can also defrost in the refrigerator overnight and then reheat on the stove or in the microwave as above.
- Try on sandwiches, burgers, egg dishes, and potatoes, in soups, stews, and sauces, as a topping for roasted vegetables or meats, in quesadillas, or on grain bowls.
Molly P says
Made this to use as a quiche filling, and it was completely delicious. Nothing better than caramelized onions, and the mushrooms take it over the top!
That's a fantastic idea! Sounds amazing. Thanks Molly!
Made these caramelized onions and mushrooms for our family's favorite burger and it was a hit! We love its rich flavor and sweetness. I'll surely have this recipe on repeat!
I'm so happy to hear the family enjoyed these!
Journa Liz Ramirez says
These caramelized Onions and Mushrooms are so good! My family enjoyed it so much and love it on repeat. Thanks, Gen, for this recipe.
yay! Thanks Journa
This was such a fabulous topping to grilled chicken sandwiches! I can't wait to make this again.
Fantastic idea! So glad you enjoyed, Wendy.
You had me at caramelized. Can't wait to try this. Thank you.
Thanks Relle! Hope you enjoy
So flavorful! We had ours on top of steak but I used the leftovers in a pasta the next day and it was perfect!
Putting these in pasta sounds amazing! Thanks Shelby
Jere Cassidy says
Made your caramelized onions and mushrooms to go over steak and honestly I could have just served this recipe by itself, my hubby loved it. Really easy to make, just gotta be patient.
Yep, people eat them straight out of the pan at my house, haha. Thanks Jere! So glad you enjoyed them.
The mushrooms take the caramelized onions over the top! I made this to serve with steaks. It was amazing! So flavorful! Everybody loved it. Next, I will serve it as a condiment with a cheese board.
Ooh, so good with steaks! Thanks Sonia.
Love this recipe so easy to make!