Air Fryer Mushrooms & Onions

If you enjoy caramelized onions and mushrooms with your steak, or as a burger topping, or just to eat, you are going to LOVE this no-fuss air fryer recipe. This method replaces standing over the stove sautéing mushrooms and onions and is pretty much hands-off except for tossing things around midway through the cooking time.

What I love most about this recipe, besides being super easy, of course, is the texture of the onions and mushrooms when they are done. They aren't crispy, but the texture is slightly firmer than when sautéed and I love that! The buttery flavor and caramelization with the slightly firmer texture are simple magic and the perfect side dish.

If you are looking for a breaded mushroom recipe made in the air fryer, be sure to check out my recipe for easy air fryer mushrooms. or for stuffed mushrooms, check out this recipe for air fryer stuffed mushrooms.

If it's crunchy onion rings you are after, try this recipe, best air fryer onion rings. Or, maybe you want a crunchy onion topping for a casserole. If so, make some onion straws and I show you how in this recipe, Green Bean Casserole with homemade onion straws.

This recipe results in a flavorful bowl of mixed onions and mushrooms that will closely remind you of sautéed mushrooms and onions like you would make in a frying pan on the stove with some olive oil and butter.

Serve these along with a sous vide sirloin steak and you will think you are dining in an upscale steak house. Don't take my word for it, though; give this classic combination a try today!

Ingredients & Substitutions

Onion

I used a Vidalia or sweet onion in this recipe because I've always loved the extra sweetness, but you can use any variety of onions that you love.

I will say that green onions are not going to work in this recipe unless you only used the white part of the onion and you would need a whole lot of green onions, so skip those. Other than that you can use yellow onion, red onion, white onion, and even shallots would work.

If you don't like onions but love mushrooms, skip the onions and double up on the mushrooms for wonderful air fryer "sautéed" mushrooms

You could also use other vegetables in place of the onions like, sliced bell peppers or even squash slices. Since squash contains more water and cooks faster, I would add them halfway through the cooking time.

Mushrooms

Cremini mushrooms or also known as baby bellas are my absolute favorite mushroom to use in this recipe. They are small like white button mushrooms, but have the flavor of portobello mushrooms which is a little more earthy flavor.

You can use sliced portobello mushrooms in this recipe if you can't find the baby bellas. The size of the mushroom isn't going to matter because you can either slice them or quarter them so they all cook at the same time.

You can also use different types of mushrooms, especially if you don't like onions and are just making air fryer buttery mushrooms. A combination of baby portobello, white mushrooms, and shitake mushrooms would be incredible.

If you don't like mushrooms, but love onions, skip the mushrooms and triple up on the onions. Since the mushrooms are bulkier and don't cook down as much as the onions do, I recommend using a total of 3 medium size onions if you are skipping the mushrooms.

You could also substitute the mushrooms with sliced bell peppers of any color if you wanted an air fryer onion and pepper side dish.

Seasonings

Basic seasonings like salt and black pepper are all you really need in this recipe, but you can also use your seasoning of choice.

I like to add a little dried thyme leaves because I love the flavor. I don't recommend using thyme powder because it is too concentrated and can overpower the vegetables.

Garlic powder and onion powder would also be nice additions, just make sure not to use too much.

If you were serving the mushrooms and onions as a pizza topping, add a pinch of Italian seasoning. If you want to serve them with a cheesesteak and want a bit of spice, add a pinch or two of red pepper flakes. I consider a pinch to be about ¹⁄₁₆ of a teaspoon, so 2 pinches would be ⅛ of a teaspoon. 4 pinches would be ¼ teaspoon.

The idea with the dry seasonings is to bring out the flavors of the mushrooms and onions, not cover them up. A little spice goes a long way, so start off with just a pinch or two of seasoning and, if you need to add more after they finish cooking, you absolutely can.

I found this out the hard way when I used too much salt in the beginning and the dish was super salty at the end and I didn't have any way to fix it. Also, keep in mind what other liquid types of seasonings you are using and take into account their salt content.

I also like to add a touch of balsamic vinegar when making air fryer mushrooms and onions. This is completely optional, but I like the touch of acid and sweetness that comes from the balsamic vinegar.

You could also use a bit of red or white vinegar, soy sauce, or Worcestershire sauce, if you prefer. It's also perfectly fine to skip the liquid seasoning.

Fat

In my opinion, it is necessary to add some sort of fat to "sauté" the onions and mushrooms in the air fryer. I realize that many people purchase air fryers to eliminate or reduce fat, so you can skip it, but if you do make sure to add some kind of liquid seasoning like balsamic vinegar or your onions and mushrooms will become too dry in the air fryer.

I like to use a combination of olive oil and butter. The olive oil coats the vegetables as they are air frying and the butter goes on at the end to create a luscious sauce that coats the veggies perfectly.

You can use any kind of oil that you like and the butter can be salted or unsalted. You can also skip the butter if you want to keep the side dish vegan.

Garnishes

Although completely optional, a little sprinkle of either dry or fresh parsley really brings a boost of color to the dish without altering the flavor.

If you skipped the dried thyme leaves and have fresh thyme, use it as a garnish and it will be amazing. A small amount of fresh rosemary is also a great option. Just don't use too much, because rosemary is a very powerful flavor.

How to Make Air Fryer Mushrooms & Onions

Prep or Mise En Place

Cut the onion in half from root end to stem end and remove the paper from the onion. Sometimes you will also need to remove the first onion layer. Lay the flat side of the onion on your cutting board and slice it into about ½" slices.

Cleaning Mushrooms can be done several ways. I use a damp paper towel and gently wipe off any dirt. You can also give them a quick rinse under cool water and pat them dry. You don't want the mushrooms to be wet when you add them to the air fryer or they will create too much steam and the vegetables won't have the same texture.

Once the mushrooms are clean, trim the stem off of the whole mushrooms and, if you are using white button or cremini (baby bella) mushrooms, I like to quarter them. You can also slice them into ½" slices, if you prefer.

If you are using large portobello mushrooms, I would quarter them and slice them so they are in bite-size pieces.

Place the sliced onions and cut mushrooms into the bottom of the air fryer basket. You do not need a rack for this, keep them on the bottom of the basket.

You do not need to preheat the air fryer for this recipe, so add the onions and mushrooms direct to the air fryer inner pot or basket before seasoning to avoid dirtying a bowl.

I have also tested this recipe in the Ninja Foodi Pressure Cooker & Air Crisper, the Ninja Foodi Indoor Grill, and the Ninja Speedi and you do not need to make any changes if using one of these appliances.

Seasonings

Add the olive oil, salt, and pepper to the mushrooms and onions and toss them around to coat.

If you want to add the dry thyme leaves and balsamic vinegar, do that now and toss to coat.

Air Frying Mushrooms & Onions

Set the temperature on your air fryer to 400℉/200℃ and the time for 30 minutes. It does not take 30 minutes for the mushrooms and onions to cook, but I like to have extra time on the clock. It usually takes anywhere from 17-23 minutes to cook the onions and mushrooms and that depends on the air fryer you are using and the texture you want them to be.

Toss the mushrooms and onions around after 10 minutes of cooking and resume air frying.

After about 17 minutes of air frying, use tongs or a fork to remove an onion slice and a piece of mushroom. Taste them to see if they are cooked enough for you. If they are, proceed to the final touches.

If you want them softer, continue air frying and check the texture after another 3-5 minutes.

Final Touches

When the mushrooms and onions are the texture you like, add in the butter and toss the mixture around. Close the air fryer and keep it off. Let it sit for 3-5 minutes to give the butter time to melt.

Toss it all around and place the air fryer mushrooms and onions into a serving bowl.

Top with dry or fresh parsley if desired.

Serve & Enjoy!

What to Serve with Air Fryer Mushrooms & Onions

Mushrooms and Onions go with just about anything and can be used in so many different ways. They can be served in a bowl as a side dish or top them with panko and cheese and bake for a casserole type of side dish.

You can use them as toppings for so many things like pizza and subs or use them as an ingredient in things like omelets, quiches, and casseroles.

Here are some of my favorite ways to use Air Fryer Mushrooms and Onions

• Steak & Cheese Sub topping
• Pizza Topping
• Top a cooked chicken breast with the onions and mushrooms and a little shredded Swiss and bake, broil, or air fry until the cheese melts.
• Top a steak with the onions and mushrooms and pour over a little béarnaise sauce or your favorite type of steak sauce.
• Use as a burger topping
• Use any leftovers in an omelet, scrambled eggs, or quiche.
• Use the mushrooms and onions in fajitas or quesadillas

These are only a few uses, there are countless ways to use and serve these delicious air fryer mushrooms and onions. So, get creative and be sure to leave a comment with your favorite way to serve them!

Frequently Asked Questions

More Delicious Air Fryer Recipes

Until I purchased the Ninja Foodi Pressure Cooker & Air Crisper, I had never owned an air fryer. Now, I have many different styles and love them all! Air fryers are perfect for making so many things, here are some of my favorites that I hope you love as much as I do.