Created by QueenBea on July 13, 2015
Step 1: Wipe any dirt from top of mushroom with a dry cloth and scrape out the stem and gills from inside the mushroom with a spoon.
Step 2: Mix together the red wine vinegar, 2 tablespoons of the pesto and the minced garlic, pour half of it into a bowl, place the mushroom gill side up into the bowl and pour the remaining mayo mixture in the mushroom.
Step 3: Let the mushroom marinate for an hour, swishing it around a few times.
Step 4: Remove the mushroom from the marinade and place cap side down onto a preheated grill over direct heat and cook for 3 to 4 minutes; season with salt and pepper.
Step 5: Turn the mushroom over and cook for another 3 to 4 minutes or until it starts to soften.
Step 6: When the mushroom is cooked to your liking, place it on a warmed hamburger bun and top with remaining ingredients.
Step 7: Enjoy!