Remove the stem and black gills from the portobello with a spoon. Wipe the portobello off with a wet paper towel to clean it.
combine the marinade ingredients in a large ziplock bag. Put the cleaned portobello in the bag and place in fridge. Leave for 30 minutes to 4 hours.
To grill: heat the grill to medium heat and cook for 5-7 minutes on each side. Add the cheese immediately after taking off of grill while still hot.
To cook in oven: Preheat oven to 425 degrees. Once heated, cook in a dish for 10-15 minutes or until tender. Add the cheese after you remove from oven while still hot.
To smoke: Smoke for 30 minutes - 1 hour before finishing on a grill with medium heat. Top with cheese right after taking off of grill.
You can also toast the buns on the grill!
Assemble like a traditional burger.
Notes
The 75 calories are just for the mushroom. Add any bun and cheese you like for the total of your entire burger. That should be around 300 calories depending on what you pick.