Place the 4 portabella mushrooms in a plastic bag and add the Italian dressing and 1/4 teaspoon of the liquid smoke seasoning. Shake the bag enough to evenly coat the mushrooms. Set aside and start to make the hamburgers.

In a small mixing bowl, combine the Worcestershire sauce, 3/4 teaspoon liquid smoke, garlic powder, pepper, and tarragon. Place the hamburger in another bowl and make a small crater in the center of the hamburger. Crack the egg into the hamburger. Pour liquid mixture into the meat. With your hands, knead the meat and the liquid mixture until they are completely combined.

Place the mushrooms and the meat back into the refrigerator and allow them to marinate for about an hour. Form four patties from the meat. Place the hamburgers and the mushrooms on your natural gas grill and cook until the hamburgers are done and the mushrooms are tender. As the hamburgers and mushrooms are finishing on the grill, place the buns on the grill to be able to toast them. Place the cheese on the hamburgers when they are just about done to allow the cheese to melt.

24 UNLV CHEFS