This is a great meatless burger option. Portobello mushrooms have a great meaty texure and are the perfect size for grilling and serving on a hamburger bun, pita bread or even on top of a salad. Once in a while you can trade a traditional meat patty for the lean protein, fiber, vitamins, minerals and antioxidants of a big old mushroom. Dress it up like burger with all the fixings and you may forget what you are missing! Worcestershire sauce contains anchovies (fish). For a vegan/vegetarian version or to avoid fish because of an allergy, substitute a vegan Worcestershire sauce, like the one made by Annie's.