We love trying out new recipes for our Big Green Egg smoker and grill and this Portobello Mushroom Burger with Balsamic Mayonnaise recipe did not disappoint. Who says grilling always has to involve meat? Definitely save this recipe for when your vegetarian friends are over for dinner! What’s best, it was easy and fast to make – always signs of a winning recipe in our household and perfect for every day Big Green Egg cooking. Just make sure you factor in time to let the portobellos marinate!

Start by making the marinade: Mince 3 or 4 cloves of garlic and combine it with 1 TB thyme (we used dried but fresh would probably be even better), 1/4 cup soy sauce, 1/4 cup balsamic vinegar and 1/4 cup olive oil. Clean your portobello mushrooms and remove the gills and stems. Place them in a zip lock bag and pour the marinade over them. Let them marinade for 30 to 60 minutes.

Use the marinating time to set-up your Big Green Egg for direct heat with the grid and preheat it to 400F. Back in the kitchen, combine 1/2 cup mayonnaise with 1 TB dijon mustard and 1/2 cup of chopped fresh basil. Brush the inside of 4 kaiser rolls with olive oil, slice a big red onion into four rings, slice a beef steak tomato and set aside four slices of muenster cheese. Once your Big Green Egg has reached 400F, place the portobello mushrooms and the onion rings on the grid. Grill them with the lid closed for two minutes on each side. Then, place a slice of cheese on each mushroom and grill and close the lid again for another minute. Finally, place the roll halves on the grid (flat side down in case there’s any doubt) and grill for another 30 seconds (at most) with the lid closed. Everything should be grilled to perfection at this point. If you feel that your onion rings may need another minute, go for it.

To assemble the Big Green Egg grilled portobello mushroom burgers spread the basil mayo on the bun halves and pile on a mushroom, a slice of tomato, a lettuce leaf and the onion ring. Complete the burger with the top kaiser roll bun and bam, you’ve got yourself a fantastically awesome tasting burger.

This recipe makes four burgers and is from of the Big Green Egg cookbook that is available for purchase at Blackhawk Hardware.