Choice of toppings such as lettuce, tomatoes, onions, avocado, vegan cheese, etc.
In a small bowl, whisk together the chopped basil and garlic, olive oil, vinegar, and tamari, and set aside. Dip each of the mushrooms in the marinade and place them on the hot grill, stem-side down. Grill the mushrooms for 5 minutes, carefully flip them over, and grill an additional 4 to 5 minutes or until tender.
Slice the buns and lightly toast on the grill, if desired. Serve the grilled mushrooms on buns with your choice of toppings and condiments.