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Quick Caramelized Sautéed Onions and Mushrooms

on August 12, 2021
last updated February 3, 2025
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This simple recipe for Caramelized Onions and Mushrooms will be a staple in your house as a delicious side dish or topper to your favorite meal!
caramelized onions and mushrooms

Looking for a flavor-punch addition to your meal? These simple Caramelized Onions and Mushrooms use a cooking technique to highlight and enhance the natural flavor of your two favorite veggies.

With just three ingredients and 30 minutes needed, you’ll find yourself whipping these up to elevate every meal. Delicious on everything from pizzas to rice bowls, or even in your Egg & Cheese Breakfast Sandwich, this versatile recipe is great to have in your back pocket.

As a mom who loves gourmet food despite a hectic schedule, I’m so glad I perfected this quick and easy caramelization hack to bring tons of flavor to my meals.

close up of cooked mushrooms and onions

Caramelized Onions and Mushrooms Ingredients


When I say this recipe is simple, I mean it! 3 simple ingredients will get you a beautiful side dish or add-on to any meal.

Here’s everything you’ll need:

  • Onion. This recipe will work with sweet onions, yellow onions, red onions, white onions, and even shallots.
  • Mushrooms. This recipe works best with white button, crimini, and baby bella mushrooms.
  • Olive oil or butter. You can use these interchangeably in this particular recipe, depending on your preference.
Onion, chopped mushrooms and oil

Quick note: Salt is optional in caramelized onions. Salt does help draw moisture out of the onions, but so does time! If you really want to expedite the caramelization process, add a dash of salt.

Caramelized Onions and Mushrooms Tips and Tricks


Caramelized Vs Sauteed

The difference between caramelized onions and sauteed onions is simply the cooking time.

Caramelized onions have to stay on the pan longer than sauteed in order to truly caramelize in the pan. I’m calling these Quick Caramelized Sauteed Onions because while they come together quickly, they still do get a nice caramelization on them.

Call it a hack, but this quick technique gets you what you want in a fraction of the time of a “true” caramelization.

Slice Your Onions First

Get your tissues ready, it’s time to slice those onions! We’re looking for thin slices about 1-3 inches long.

If you have an onion slicing technique you know and are comfortable with, go for it! Just try to get those slices nice and thin. If you’re looking for guidance on slicing your onions, I’m here for you.

Here’s a step-by-step on how I slice mine:

Step 1: Slice the onion roughly in half, next to the bulb.

Step 2: Slice about 1/2 an inch off of the top and discard it.

Step 3: Peel back the outer layers and discard them.

Step 4: Lay the onion flat and slice it into thin strips, separating the layers from one another.

Step 5: For the other half, cut next to the bulb again and repeat steps 2-4

Step 6: Finally, cut the bulb off, discard, and repeat steps 2-4 one final time.

And if you’re a visual person, see below!

Slicing yellow onion in half.
Step 1
Slicing the top off of half an onion.
Slice the top off
Peeling back the outer layers of the onion.
Peel back the outer layers and discard
Slicing half of an onion into strips.
Lay the onion flat and slice in strips
Cutting into half of an onion next to the bulb.
For other half, cut next to the bulb again and repeat steps 2-4
Cutting bulb off the onion
Finally, cut the bulb off, discard, and repeat steps 2-4 again

Add Your Onions to the Pan

It’s important to add your onions to the pan first, before the mushrooms. They need about 10 minutes more cooking time than the mushrooms.

Adding your onions and mushrooms at the same time will risk either your onions being undercooked or your mushrooms being overcooked.

Add the oil or butter to the pan with the onions and let them cook for about 10 minutes until they start to brown. Stir them every 3 minutes or so just so they don’t stick to the pan and burn.

If it seems a little too dry, you can add 1-2 tablespoons of water to the pan.

Sliced onions caramelizing in a pan.
Let the onion sauté in butter in a frying pan for about 10 minutes first.

Prep Your Mushrooms Next

Rinse your mushrooms and pat them dry. Carefully hold your mushrooms on your cutting board, stem up. Then, slice them into 3 or 4 thin pieces, as pictured below.

Slicing mushrooms with knife.
Clean and slice the mushrooms.
sliced baby bella mushrooms on a chopping board with knife
You should be left with roughly evenly sized mushroom pieces.

Mix ‘Em, Then Let ‘Em Sit

Once your onion starts to brown, add your sliced mushrooms and mix well, so they are evenly distributed throughout your onion slices.

Now the next step is key. Because if you’re anything like me you are impatiently hovering over your food as it cooks, and, well, you may be tempted to give it a stir or two.

But, from here on out, this recipe is hands-off!

In order for the onions and mushrooms to perfectly caramelize, simply let them be! Give it a good 5-8 minutes before using a spatula to turn them to caramelize both sides.

Mixing sliced mushrooms into stir fried onions.
Add the sliced mushrooms to the pan with the onions.
Baby bella mushrooms and yellow onions caramelized in frying pan.
Sauté for 5-8 minutes tossing occasionally.

Hot ‘N Ready

You’ll know your caramelized onions and mushrooms are ready when they have a nice golden-brown color. I like to sprinkle mine with a little sea salt to ramp up the flavor.

How to Properly Store and Reheat Leftover Caramelized Mushrooms and Onions

These Caramelized Onions and Mushrooms will stay delicious in an airtight container in your refrigerator for about 5 days.

You can also opt to freeze them to make them last longer. Store them in an airtight container in the freezer for up to 3 months.

These reheat VERY well in a pan over medium heat. Just add them directly to the pan, no need for more oil or butter. Stir frequently until heated through (about 5-8 minutes, or 10-12 from frozen).

Serving Caramelized Onions and Mushrooms

I’m tempted to say “with EVERYTHING” because I’m SO IN LOVE WITH THEM. But, to be more specific, they work great on all kinds of burgers and sandwiches.

Like on this this Black Bean Burger, and this Veggie Sandwich.

They’re also outrageously delicious on tacos, pizza, in breakfast burritos—the options are endless!

caramelized onions and mushrooms in a serving bowl with gold serving utensils

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Why You Should Make These Caramelized Onions and Mushrooms


  • They’re simple. This recipe uses a simple technique to bring out the natural flavors of the produce.
  • They’re super flavorful. A healthy and natural flavor-punch to any dish.
  • They’re good on pretty much everything. I will never say no to caramelized onions and mushrooms on anything! Well, anything savory that is.
caramelized onions and mushrooms

Quick Caramelized Sautéed Onions and Mushrooms

5 from 15 votes
Marley Goldin
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This simple recipe for Caramelized Onions and Mushrooms will be a staple in your house as a delicious side dish or topper to your favorite meal!
Prep Time 5 minutes
Cook Time 20 minutes
Total Time 25 minutes
Servings 2 servings

Ingredients
  

  • 1 large yellow onion
  • 1 tbsp oil or butter of choice
  • 8 ounces baby bella or white mushrooms
  • ¼ teaspoon salt (optional)

Instructions
 

  • Slice your onion thin (see post section above for detailed instructions) and add it to a frying pan with your oil or butter on medium heat.
    1 large yellow onion, 1 tbsp oil or butter of choice
  • Rinse, dry, and slice your mushrooms.
    8 ounces baby bella or white mushrooms
  • Continue to sautee the onions over medium heat for about 10 minutes, stirring occasionally with a spatula or wooden spoon, until the onion starts to brown around the edges.
  • Add the sliced mushrooms and mix well, so that the mushrooms are evenly distributed throughout the onion slices.
  • Leave the onions and mushrooms over medium heat for 5-8 minutes without stirring to allow for caramelizing process to occur.
  • Once the onions and mushrooms are golden brown on the bottom, stir a couple of times to turn them, and cook for another 5 minutes or so, allowing them to caramelize on both sides.
  • Add salt to taste (optional) and serve hot as a side or topping to any savory dish!
    ¼ teaspoon salt

Pro Tips

  • Use 1 tablespoon of butter or oil per 1 onion and 8 ounces mushrooms. If you are halving the recipe, use 2 teaspoons of oil or butter.
  • To reheat, just add the caramelized onions and mushrooms back to your frying pan over medium heat until they are heated completely through, about 5-8 minutes.
Course Basics and Bases, Sides
Cuisine American
Diet Vegan
Keyword Caramelized Onions, Easy, Mushrooms, One-Pot
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6 thoughts on “Quick Caramelized Sautéed Onions and Mushrooms”

  1. 5 stars
    This recipe is wonderful. Had it for dinner with lamb chops and husband put what was left in his morning omelet.

5 from 15 votes (13 ratings without comment)

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