Carefully wash the portobello mushrooms and pat them dry with paper towels. Remove the stems and pierce the mushrooms all around with a fork.
Make the marinade by mixing the balsamic vinegar, olive oil, oregano, garlic powder, paprika, salt, and Sriracha in a bowl.
Drizzle the mushrooms with the marinade until they are covered and then let them rest for 10-15 minutes so they absorb it.
Place the portobello mushrooms on the grill pan with the gill sides up. Grill them for about 5 minutes.
Flip the mushrooms and grill them for another 4-5 minutes, brushing them with marinade drippings for extra flavor.
Add-ins and Substitutes
Add some heat- Up the spice factor with these Vegan Grilled Portobello Mushrooms by adding extra Sriracha, red pepper flakes, or cayenne pepper to the marinade. You can also use Chipotles in Adobo Sauce.
Substitute different mushrooms. Besides portobello mushrooms, you can also make this with baby Bella (cremini), white button, or shiitake mushrooms.
Add liquid smoke. Go extra smoky by using liquid smoke in the marinade as well as grilling the portobello mushrooms. You can also bake or pan-fry them with the liquid smoke to get the flavor.
Substitute the marinade. You can also make this marinade with steak sauce, soy sauce, ginger, red wine vinegar, and white wine. Change up the flavor profile of this dish with variations on the marinade.
How to Store
These Vegan Grilled Portobello Mushrooms are best on the same day they are made, but you can store them in the fridge for 2-3 days in an airtight container. Reheat them either in the microwave or on the grill until warmed through. You can add some more marinade if you choose to reheat them on the grill.