I’m going to show you how to make a delicious grilled portobello mushroom sandwich with a homemade BBQ sauce & cheese sauce (vegan-friendly)! You can cook your portobello mushrooms on the barbeque grill or grill them on the stove.
If you’re craving a mouth-watering grilled portobello sandwich or burger, you’re going to love this recipe! I highly recommend you also make my quick Guinness BBQ sauce for this sandwich but you can use any BBQ sauce you have at home!
Related Recipe: Guinness BBQ Sauce
Grilled Portobello Mushroom Sandwich
VEGAN & DAIRY-FREE
I’m going to show you how to marinate and cook your portobello mushroom for your sandwich! I was inspired to make a vegan “mushroom steak” to put on the sandwich using a marinade that makes the mushrooms super flavourful.
If you want to take your sandwich to the next level, I’ve also included instructions on how to make a beer cheese sauce, caramelized onions, and recommendations on what to add to your portobello sandwich.
INGREDIENTS FOR GRILLED PORTOBELLO SANDWICH:
- Portobello Mushrooms
- Olive Oil
- Balsamic Vinegar
- Liquid Smoke
- Steak Spice Seasoning (whichever you prefer)
- BBQ Sauce or Vegan Worcestershire Sauce
- Sourdough Bread, Burger Buns or Rolls
- Red Onions
- Optional Toppings: Pickles, Horseradish
OPTIONAL INGREDIENTS FOR A BEER CHEESE SAUCE:
KITCHEN EQUIPMENT I USED:
- large portobello mushrooms, stems removed (I used 4)
- 2 tbsp olive oil
- 3 tbsp balsamic vinegar
- ½ tsp liquid smoke
- 3 tbsp steak seasoning, whichever you prefer
- 1 tbsp bbq sauce of choice or vegan Worcestershire (I used)
- 3-4 tbsp my Guinness BBQ sauce or your preferred BBQ sauce
- 8 thick slices sourdough,4 burger buns or rolls
- handful of greens
- 2 red onions, cut into thick slices
- optional toppings: pickles, horseradish
- Make your marinade in a large Tupperware or shallow bowl, by adding olive oil, steak spice seasoning, bbq sauce or vegan Worcestershire, balsamic vinegar, and liquid smoke. Whisk everything in the bowl until combined.
- Place the mushroom caps into the bowl and brush the marinade all over the mushrooms (top & bottom). They do not need to be submerged in the marinade or anything- but they should be coated completely. Allow the mushrooms to sit stem-side up & allow them to marinate for 20-30 mins minimum in the fridge. The longer you marinate the stronger the flavour will be. You could marinate overnight.
- When ready to cook, heat a pan over medium-high heat, and pour in a little bit of the leftover marinade, and discard the rest but keep the bowl.
- When piping hot, add the mushrooms to the pan, stem-side down, leaving plenty of space between them. Allow them to cook for 3-5 mins until the liquid begins to release.
- Reduce heat to medium.
- Take a heavy cast iron pan (or something slightly heavy), and place it on top of the mushrooms to flatten the portobello mushrooms. Press to flatten gently. Cook for another 2 mins.
- Flip the mushrooms, and repeat flattening with a cast iron pan for a few minutes. You can add some water to deglaze the pan if you wish.
- Remove the cast iron pan, and flip again so they are stem-side down. Turn the heat back up again.
- Allow the mushrooms to cook until the liquid is evaporated, roughly 3-5 mins.
- Next, remove from the heat
- If you want to BBQ your portobello mushrooms for a smokey grilled and char taste, first place the mushrooms into a bowl and toss with a few tbsp of my Guinness BBQ sauce or BBQ sauce of choice.
- Preheat your BBQ to medium-high heat.
- Sear the portobello mushrooms on the grill for a couple of minutes on each side, until you get a slight char. Transfer to a cutting board, and thinly slice.
- Meanwhile, smear a bit of butter on the face of each bun, and toast on the grill until nicely charred.
- Spread some BBQ sauce on the bottom of each bun and place a handful of greens, topped with a generous pile of mushrooms slices.
- I added some caramelized onions and a drizzle of my Guinness beer cheese.
- To make caramelized onions for your sandwich, heat 1 tbsp olive oil in your pan, over medium-high heat.
- Add red onions and a pinch of salt and cook 8-10 mins, until caramelized, adding a little bit of water as needed to deglaze the pan.
- To make a creamy beer cheese sauce for your sandwich, start by melting ¼ cup butter in a medium saucepan over medium heat.
- Whisk in the ¼ cup flour, and cook for 2 mins, whisking constantly.
- Add the 1 tbsp mustard, and slowly begin pouring in ⅓ cup Guinness or beer of choice, whisking constantly. Cook for 1-2 mins, whisking. FYI if you're worried about adding alcohol just know that the alcohol gets cooked out of the beer.
- Then slowly whisk in 1 cup of soy milk or oat milk. Whisk until you smooth.
- Turn down to medium-low and add your dairy-free shredded cheese, stirring to help it melt. You can add more of your milk until you reach your desired consistency. I like a pourable sauce. Voila!
Looking For More Vegan Sandwich Recipes?
- Vegan Philly Cheesesteak Sandwich
- Vegan Popeyes Chicken Sandwich
- Thanksgiving Leftover Sandwich Idea
Made this recipe? Let me know what you think by leaving a ★★★★★ star rating & comment below. It truly helps me & I really appreciate any support! Feel free to share your food photos on social and tag me @edgyveg so I don’t miss it!
Share My Recipe on Pinterest!