Mushroom Burgers with caramelized Onions

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These mushroom burgers with caramelized onions gave me all the feels!I haven’t had a big fat burger in awhile, not cutting out meat or anything, but for some reason some time has passed since I enjoyed one. So how about a big beef burger, caramelized onions, the mushrooms all topped with a rosemary and black pepper mayo artisan bun. Yum, yum and yum!

I normally just do a plain beef burger, topped with just about everything I can add to it. This burger was born from a collaboration on Instagram featuring… you guessed it, mushrooms.

Preparing the mushrooms and onions

So, start this burger with your these lovely little fungi. I used a simple white mushroom, bought in the bulk at Costco. Slice the mushrooms for sauteing.

woman slicing with mushrooms with a chefs knife on a white cutting board

While I was slicing the mushrooms, I felt like caramelized mushrooms would need a place on these burgers too. They were sliced the same time.

woman slicing onions on a white cutting board with a chef's knife

Add the mushrooms to a hot pan with a little olive oil. I also sprinkle with salt and add a little minced garlic. Mix these occasionally. They will cook and begin to shrink substantially within 5 minutes.

sauteing mushrooms in a small nonstick pan

I had the onions caramelizing at the same time too. Caramelize them on a medium low for at least 15-20 minutes.

caramelizing onions in a small nonstick pan

Rosemary and black pepper mayo

Now, on to your rosemary black pepper mayo. It’s simple. Add your mayo, rosemary, black pepper and lemon juice to a small bowl and mix.

woman mixing rosemary into mayonnaise

The burger

Everything else is ready, so not let’s get those burgers started!

woman sprinkling burger with seasoning

You can grill your burgers, but I love to do mine in a cast iron skillet. Lodge is my favorite!

cooking beef burgers in a cast iron skillet

Assembling the mushroom burgers with caramelized onions

Time to assemble!! I bought the artisan rolls at Costco. If you want to make your own, that’s great! Add the burgers.

woman add burgers with melted swiss onto artisan bun

Layer on those caramelized onions.

woman adding caramelized onions onto burger with swiss

Pile on those mushrooms! I promise you, they make the burger!

woman adding sautted mushrooms onto beef burger.

You can add the mayo on the top or bottom. I added mine on the top!

woman spreading aioli onto burger bun

Top it off and it’s done!

woman preparing a mushroom burger with caramelized onions

This burger is huge. It’s intense. It isn’t for everyday, but it is so good when it does happen.

mushroom burger with caramelized onions

Other options

While I love these mushroom burgers with caramelized onions are amazing, I realize they are not for everyone. If you are looking for a lighter option? What about these teriyaki chicken burgers? Or if beef isn’t your thing, what about these black bean burgers?

mushroom burger with caramelized onions
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5 from 1 vote

Rosemary and black pepper aioli

This is a great condiment for any sandwich or burger of choice!
Course condiments
Cuisine American
Keyword aioli, rosemary aioli, rosemary black pepper aioli
Prep Time 5 minutes
Total Time 5 minutes
Servings 6 servings
Author Amy- A Red Spatula

Ingredients

  • 1/3 cup mayo
  • 1 teaspoon rosemary, crushed or ground
  • 1/2 teaspoon ground black pepper
  • 1 teaspoon lemon juice

Instructions

  • Mix all ingredients until well blended.
    Store in airtight container for up to one week.
    Now, sit back and enjoy. You deserve it!
Print Pin
5 from 1 vote

Sauted Mushrooms

Perfect sauted mushrooms are so simple to make and add so much flavor to any burger!
Course Side Dish
Cuisine American
Keyword mushrooms for mushrooms burger, sauted mushrooms
Prep Time 2 minutes
Cook Time 5 minutes
Total Time 7 minutes
Servings 4 servings
Author Amy- A Red Spatula

Ingredients

  • 5 cups sliced mushrooms I used plain white muchrooms, but use whatever mushrooms you prefer
  • 2 teaspoons olive oil
  • 1 teaspoon minced garlic
  • 1/4 teaspoon salt

Instructions

  • Heat nonstick or cast iron skillet over medium heat. Add olive oil and heat. Next add in mushrooms, salt and garlic. Cook, stirring occasionally until the mushrooms are tender and have shrunk. Mine took about 5 minutes.
    I prefer to use my mushrooms right away. They can be stored in an airtight container for up to 2 days if you need to.
    Now, sit back and enjoy. You deserve it!
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5 from 1 vote

Caramelized onions

Simple onions that pair perfectly with most burgers and sandwiches.
Course Side Dish
Cuisine American
Keyword caramelized onions, onions for sandwiches
Prep Time 5 minutes
Cook Time 20 minutes
Total Time 25 minutes
Servings 4 servings
Author Amy- A Red Spatula

Ingredients

  • 3 cups sliced onions Mine were sliced at about 1/8 inch
  • 2 teaspoons olive oil
  • 1/4 teaspoon salt

Instructions

  • Heat a nonstick skillet over medium heat. Add olive oil and heat. Add in onions and turn heat to medium low. Add salt. Saute, stirring occasionally until the onions have turned a deeper caramel color. This will take awhile, so be patient. It will probably take at least 20-25 minutes.
    You can use them right away or even store them in an airtight container in the fridge for up to 4 days.
    Now, sit back and enjoy. You deserve it!
Print Pin
5 from 1 vote

Burger seasoning

This is my go to seasoning for burgers and steaks. It is simple to throw together and so yummy!
Course condiments
Cuisine American
Keyword burger seasoning
Prep Time 5 minutes
Total Time 5 minutes
Servings 4 servings
Author Amy- A Red Spatula

Ingredients

  • 2 tablespoons kosher salt
  • 1 teaspoon ground black pepper
  • 1 teaspoon garlic powder
  • 1/2 teaspoon paprika
  • 1/2 teaspoon cayenne pepper

Instructions

  • mix all ingredients well.
    Sprinkle generously over the burgers and cook as desired.

About The Author

Amy

3 COMMENTS

  1. Mushroom Burgers with caramelized Onions — A Red Spatula | My Meals are on Wheels | 29th Jul 20

    […] via Mushroom Burgers with caramelized Onions — A Red Spatula […]

  2. Brooke | 2nd Aug 20

    5 stars
    You had me at burgers but man, those onions and mushrooms realllllyyyy got me!

    • admin | 7th Aug 20

      Oh, yes. One of our favorite burgers!! Thanks Brooke!

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