These sweet and savory Portobello Mushroom and Caramelized Onion Sliders will have you wanting more! Portobello mushrooms marinated in balsamic vinegar and Dijon mustard with sweet caramelized onions on your favorite bun, what's not to love?
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I have been wanting to make a portobello mushroom sandwich for the blog for a while now. These Portobello Mushroom and Caramelized Onion Sliders are finally getting a debut because I was on a sandwich-making kick recently.
I fell in love with portobello mushroom sandwiches on my first trip with my husband. This was quite a few years before I knew I was gluten intolerant so there were more options for me eating out.
On the trip I had three vegan portobello mushroom sandwiches at three different restaurants because they looked like the best choice on each of the menus.
I was happy with every single one of them and not at all tired of eating the same thing several times on the trip.
The ingredients that add a ton of flavor to the mushrooms are balsamic vinegar and Dijon mustard.
Not only are the mushrooms marinated in balsamic vinegar and Dijon mustard, but they are also cooked down in the marinade as well.
You may taste the mushrooms and think that the flavors are quite strong, but once you combine them with your favorite buns and some sweet caramelized onions, you will taste the symphony of flavors that the mushrooms become part of.
Caramelized onions are one of those ingredients that elevate anything that you add them to. In fact, I would recommend doubling the amount so that you can use them in other dishes.
Tips
- For caramelized onions you need some patience. It takes a good 40 minutes to get nicely browned onions. Slow and steady wins the race.
- If the onions start to stick, add a little water, like a quarter of a cup or so.
- Balsamic vinegar adds a wonderful flavor to caramelized onions. I always add a couple of splashes near the end of the cooking time.
- Make a double batch of the caramelized onions and add them to a Vegan Caramelized Onion and Mushroom Grilled Cheese, a baked potato, or Vegan Mashed Cauliflower with Caramelized Onions and Mushrooms.
- Make a double batch of the whole recipe and add half of it to pasta with the Maple Dijon Mayo and some steamed asparagus.
- Cook mushrooms in marinade for more intense flavor.
- The type of bread / buns that you use makes a big difference in the overall taste of the sandwiches.
Other Vegan Sandwiches
The combination of flavors in these vegan portobello mushroom sliders is rich and satisfying. If you love this recipe, please come back and leave your feedback and star rating.
📋 Recipe
Portobello Mushroom and Caramelized Onion Sliders
Ingredients
Portobello Mushrooms
- ½ cup balsamic vinegar
- 3 tablespoons Dijon mustard
- 2 tablespoons olive oil
- 2 portobello mushrooms
- Salt
Caramelized Onions
- 2 cups sliced onion
- 2 tablespoons olive oil
- 2 tablespoons balsamic vinegar
- Salt
Maple Dijon Mayo
- ¼ cup vegan mayo
- 2 tablespoons Dijon mustard
- 2 tablespoons maple syrup
- Buns - I used Pamela's gluten free pizza mix
Instructions
Caramelized Onions
- Add olive oil to a hot pan. Add sliced onion and cook on medium-low heat for about 35-40 minutes, or until onions are caramelized. Add balsamic vinegar to deglaze the pan. Add salt. Remove onions.
Portobello Mushrooms
- Wipe mushrooms with a damp towel and slice into ½ " slices. Mix balsamic vinegar, Dijon mustard, and olive oil. Marinate the mushrooms for at least an hour.
- In the same pan that you cooked the onions, place marinated mushrooms and marinade. Cook on medium heat until mushrooms are tender and marinade is cooked down.
Maple Dijon Mayo
- Mix all ingredients.
- Slather Maple Dijon Mustard on buns. Add portobello mushrooms and caramelized onions.
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Nutrition
*Note: Nutrition information should be considered an estimate only. Different nutrition calculators give you different results. Also note that the buns were not calculated into the nutrition info.
Jessica says
I made these this week for my husband and kids. Everyone loved them! Thanks for the great recipe!
Willow Moon says
Thanks Jessica, I am glad you and your family liked them!
Lindsay says
How did you make the buns?
Willow Moon says
I used Pamela's pizza mix. They have directions on their website for how to make the buns. I was really excited when I found out you could make buns with it because my previous favorite pizza mix didn't have that option.
Ashley @ GrowingSpangs.com says
You know, I have never really gotten on the portobello mushroom team, although I have wished I was for a long time. Honestly, this might be the way I could like them - caramelized onions and sauce make anything amazing, and I would love to be more vegetarian. I'll have to give this a try, thanks!
Willow Moon says
It is definitely all about what you pair with them!
Cat says
Mmmm these sliders looks so tasty! Definitely going to make some this weekend!
Willow Moon says
I hope you like them as much as I do!
Daniela says
YUM! I just recently gained the love of portobello mushrooms after many years of deciding I hated them. I became a vegetarian a year ago, though, so I was determined to acquire the taste of them!
Willow Moon says
It's funny you mention that, because I go through phases of loving mushrooms, then not wanting anything to do with them for awhile.
Eva says
These look so good! What kind of salad do you recommend serving them with?
Willow Moon says
I would pair it with a salad that has light and fresh flavors since the sliders are quite rich. Maybe something with cucumber or even strawberries, and a light dressing that is vinegar based.
Kate | The Organized Dream says
These sliders look delicious and I can only imagine how good it must taste with balsamic vinegar! That's one of my favorites to use!
kristen says
wow, this looks amazing! I love portobello mushrooms and I bet they're even better with the balsamic and caramelized onions! Thanks for sharing!
Willow Moon says
They definitely add a ton of flavor!
daneen rogers says
Oh these look soooo good! I love carmelized onions too, especially carmelized red onions! I'm definitely going to have to try this recipe for a meatless meal one night!
Willow Moon says
I love caramelized red onions too, but then I will eat any kind of caramelized onions!
Carrie | Clean Eating Kitchen says
I love portobello mushrooms in burgers and those onions look awesome! Thanks for sharing!