Easy Caramelized Sauteed Mushrooms and Onions

These caramelized mushrooms and onions are so easy to make and bring an amazing deep flavor to so many dishes. They are done within 30 minutes and pair well with burgers, pasta, rice, risotto, sandwiches and more. Plus, this recipe is vegan and gluten-free!

This recipe is super simple and amazing for when you need a speedy and versatile side dish or topping without having to put in much work. 

We often prepare these caramelized mushrooms and onions to serve in burgers, but they are great over mashed potatoes, in sandwiches, mixed in gravy, over rice or grain bowls and in pasta. You will find yourself using them in so many ways!

Sauteeing mushrooms and onions together is actually a perfect match: they both caramelize well, they complement each other in texture and they go well served with similar dishes.

This recipe also is ridiculously easy. I would even say that this is barely considered a recipe! It's all about using fresh produce of good quality. Plus, following a simple cooking technique is important to ensure that the veggies caramelize in a way that enhances their flavors, which also creates a perfect soft and chewy texture.

I'll share all my favorite flavor boosters if you want to personalize your version, but here I kept it very simple so it pairs well with just about everything and to allow some room for customization.

Let me know if you gave it a try and please share with us how you served them! ❤️

Why this recipe works

• Makes for such a tasty staple to boost the flavor and add more layers of texture to so many dishes
• Healthy recipe that's lower in fat
• Simple recipe and easy to make
• Can be done within 30 minutes (mostly hands-off time)
• Can be used as a topping or side dish
• Vegan and gluten-free

Ingredients you will need

• Onions: You will need a large onion to make this recipe. Yellow onions and Spanish onions are great since they caramelize well (they have a good amount of natural sugars). Red onions or sweet onions (such as Vidalia) also have more sugars and caramelize well, although they might give a sweeter result to this recipe. That being said, any kind of onions will caramelize, so use and experiment with what you've got.
• Mushrooms: you will need an 8oz container of mushrooms for this recipe. Regular white mushrooms work well, but cremini (baby bella mushrooms) work very well too. You can caramelize other types of mushrooms as well, such as oyster mushrooms or even shiitake. 
• Olive oil: you need a little oil or butter to help caramelize. If you are following an oil-free diet, then know that you can also make them without any added fat, although the vegetables might not caramelize as easily. 
• Salt: add to taste.

How to make caramelized mushrooms and onions

Caramelizing mushrooms and onions together is easy, but the trick is to cook the sliced onion first as it takes more time to caramelize. Also, allow some time for the vegetables to cook properly, about 30 minutes total. This will make all the difference between simply sauteeing vegetables vs caramelizing them.

Slice the onion

Slice the onion in half going through the apex or bud part. Then, remove both apexes. Peel and slice in half once more following the orientation of the layers. Finally, cut the onion into thin slices of about ¼-inch thickness.

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Sauté the onion

Warm up a large skillet over medium heat with a bit of olive oil and then, add the sliced onion with a pinch of salt. Stir them in the oil and then disperse them in the hot pan in a single layer. Let them cook on medium heat for about 10 minutes before adding the mushrooms and try not to constantly move them around so they can brown and caramelize.

Add the mushrooms 

While the onions are cooking, then clean and pat dry the mushrooms. You can rub them with damp paper towels or run them under cold water (pat them dry right away after). Then, slice them in about ¼-inch thick slices and set them aside.

Once the onions start to turn golden brown and have been cooking for about 10 minutes, then add the sliced mushrooms, a little more salt and stir them in the pan. You can add more olive oil if needed.

Spread the vegetables in the pan and then, let them cook still at medium heat (or even low heat) for about 5-6 minutes at the time before touching them. Keep cooking for another 15-20 minutes total or until they are done to your liking.

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Finish up and serve

Once the sauteed mushrooms and onions are done, you can sprinkle some coarse salt over them before serving. Also, feel free to add a handful of fresh herbs (especially fresh parsley) for flavor and to give the dish a nice punch of color.

Caramelizing vegetable tips

Caramelizing mushrooms and onions is so simple and really does not need much attention. But, there are a few simple tricks to create the best caramelized flavor and texture:

• You cannot really rush this recipe. For a deep savory flavor typical of caramelized onions, you really need at least 30 minutes of cooking time to allow the natural sugars to develop. Or even longer than 30 min if you can!
• Pat dry the vegetables very well. You do not want to add too much extra moisture to the pan so they sear and caramelize instead of steaming.
• You can add more oil if you want, which can also help the caramelization process and the texture to turn soft and creamy.
• Do not slice the vegetables too thin, especially the onions, or they might burn more easily.
• Do not cover the pan: if you do, then the moisture will get trapped inside and steam the vegetables, preventing them from browning in the pan.
• To caramelize, it is best to cook on lower heat for a longer period of time. They can be ready after about 30 min total, but you can caramelize them even longer. 
• And probably the most important tip: do not constantly stir in the pan. The onions and mushrooms need to be still in the pan for a few minutes at a time so they brown and caramelize.

What kind of pan should I use?

Using a larger pan will allow you to spread out the vegetables nicely, which means that they will caramelize more evenly and better (the moisture will be able to escape more easily).

Technically talking, a cast iron skillet might be the best choice to caramelize vegetables. If you were planning on using plenty of olive oil and even maybe adding some butter, then this is what I would go for (it might stick to the bottom of the pan without the fats).

I prefer using a non-stick skillet or pan as it allows me to go slow on the extra added fat, making this dish a little healthier. But you do you.

Serving suggestions

This dish is so versatile and great served with so many meals. You can use them as a side dish or they also make for a perfect topping for a main dish. Here are my favorite pairings for this recipe:

• Pizza: use them to garnish flatbread, focaccia, pizza (try them with this white sauce pizza!) or to stuff in calzones.
• Burgers: this is probably our favorite way to serve them. They are especially perfect layered in jackfruit burgers.
• Tacos: this can be a fun way to serve the leftovers. Pair with a lentil walnut taco meat and a vegan tofu sour cream.
• Sandwiches: especially amazing in sub-style sandwiches with vegan meatballs and marinara sauce.
• Pasta or risotto: serve over a simple oat milk Alfredo pasta or layer in lasagna dishes.
• Mixed-in sauces: perfect to toss in a vegan white sauce and serve over pasta. Or during the holiday season, use them to garnish mashed potatoes and gravy.
• Toasts: my favorite way to enjoy the leftovers the next day is simply over toasts, with either hummus or pesto, if I have some ready to go. It makes for a simple yummy lunch!

Variations

Caramelizing mushrooms and onions is super simple, but also, there is also a lot of room to add more flavors depending on what you are looking for and how you will serve them. 

Also, if you have to speed up the cooking process because of a lack of time, then the onions might not have had enough time to develop that deep savory taste. In that case, you can add some extra ingredients to the pan to enhance the overall flavor. 

Here are a few flavor booster ideas:

• Butter: the most common ingredient to add to a pan of caramelizing onions. I only use vegan butter, which would work well here. You can add it at the beginning of the cooking process or at the end of cooking the veggies if you find that they need a boost in flavor. Or during the holiday season, I would definitely add butter to make them luxuriously rich and amazing.
• Sugar: I never add sugar (brown sugar or maple syrup), but adding a small amount can speed up the process. Or at least, it can make the vegetables taste sweeter if you cook them too fast for all the natural sugars from the onions to develop (although some might say that this is cheating!).
• Balsamic vinegar or Worcestershire sauce: just a hint can add more sweetness or a nice tangy touch to the veggies.
• Garlic: great to add more flavor that pairs so well with both mushrooms and onions. Add it completely at the end and then cook for 2-3 minutes extra while stirring often.
• Herbs: I like serving this recipe sprinkled with fresh herbs, but you can also include some in the pan or even some dried herbs when cooking the veggies. Fresh thyme would be a great way to flavor them.
• White wine: you can add some wine for a huge boost of flavor. In that case, follow the recipe as is until completely done caramelizing and then, add the wine (about ⅛-1/4 cup). Keep cooking until the liquid is mostly evaporated without drying the onions.
• Red pepper flakes: for some mild heat, add a pinch of red pepper flakes to the pan.

Storage tips

Caramelized onions and mushrooms store pretty well. Keep leftovers in an airtight container in the fridge for up to 4 days. You can reheat using the microwave or in a pan.

FAQ's

More side vegetable recipes you might like

• Harissa potatoes
• Spanish pisto
• Oven-roasted potatoes and broccoli
• Vegan twice baked potatoes
• Miso glazed aubergine
• Mashed purple sweet potatoes
• Vegan zucchini fritters
• Vegan cauliflower gratin
• Vegan stuffed mushrooms
• Lemon miso roasted potatoes
• Vegan potato croquettes

I hope you like this caramelized mushrooms and onions recipe as much as we do! If you try it, please leave a comment below and rate the recipe to let me know how it was. Your feedback is so helpful!

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