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Portobello mushroom burgers are a proven hit with vegans, vegetarians and omnivores alike! These juicy sandwiches are made with hearty mushroom caps slathered in a zippy Dijon mustard sauce. Cook them up in the oven or on the grill!

So, it’s August, which means it’s late summer, and the perfect time for one of those recipes that gives you the option of cooking with the oven or the grill. Okay, maybe grilling is ideal for this time of year, but I’m a little excited about fall and the prospect of firing up the oven. You can make up your own mind though!
Either way, you should make these portobello burgers.
Also, I should mention that even if you don’t have a grill/choose not to grill them, they are so incredibly easy that you totally won’t break a sweat during preparation and therefore won’t mind the little bit of extra heat in your home at all.
What I really like a about roasting, and what drives me to continue to do it through the summer months is probably the fact that I can toss something together super quick, stick it in the oven, and then walk away. Twenty, thirty, forty minutes go by, I don’t even remember I did anything, and then the buzzer reminds me of my awaiting meal. Super easy!


Ingredients You’ll Need
- Portobello mushroom caps. Choose large, sturdy caps that look really fresh. Keep in mind that they will shrink when you cook them, so don’t worry too much if they appear too large for burger buns.
- Whole grain Dijon mustard. The key to this recipe is the mustard. Pick a really good one! I’m a big fan of Trader Joe’s whole grain Dijon mustard. If you have another favorite Dijon mustard, by all means, use it, but please don’t go out to the supermarket and pick up any junky old generic Dijon for this recipe. It just won’t be the same.
- Olive oil.
- White wine vinegar. Red wine vinegar or even plain old white vinegar will do if that’s what you have on hand.
- Maple syrup.
- Garlic.
- Salt & pepper.
- Burger buns. Feel free to use fancy buns if you’d like! A nice ciabatta bun would work really well.
- Toppings. These are truly delicious on their own, but I do love a good burger with toppings piled high, so go for it if you do too. Try lettuce or other greens, sliced tomato, onion, vegan mayonnaise, sprouts, or even sliced vegan cheese.
How They’re Made
The following is a detailed photo tutorial on how to make this dish. Scroll all the way down if you’d like to skip right to the recipe!


To make your sauce, whisk Dijon mustard together with minced garlic, white wine vinegar, olive oil and a touch of maple syrup.


Clean up your mushrooms, remove the stems, and use a spoon to scrape out the gills.
Tip: Some folks like to leave the gills in their portobello mushrooms, and you can if you’d like. I prefer to remove them because they can get when cooked.


Brush your mushrooms with the sauce. You’ll probably have some extra sauce. Hang on to it!


Roast or grill your portobello caps until they’re tender. If you’re grilling them you’ll want them lightly charred.
Stuff the mushrooms into buns and pile on your toppings of choice. Your portobello mushroom burgers are ready to serve!


Leftovers & Storage
Leftover portobello mushrooms can be stored in an airtight container in the fridge for about 3 days.