Preheat oven to 450. Lightly spray a glass baking dish or casserole type dish with a non-stick spray.

Remove stems from mushrooms (don't throw them away) and place mushroom caps in the baking dish so that you are looking at the underneath side.

Sprinkle each mushroom with soy sauce and Worcestershire, about 2-3 Tbsp (more if you like.) I just shake it over the mushrooms until the caps are holding the liquid. Season with pepper, several grinds over each. Replace stems back into the mushroom caps.

Bake for 15 minutes, less for a smaller sized mushroom. (some are huge)

Sauté the sliced onion in a hot skillet for about 5 minutes. Set aside.

Toast buns if preferred. Top one side of the bun with Dijon, and the other side with hummus. Then add tomatoes, cooked onions, and fresh spinach. When mushrooms are finished baking remove the stem and add the mushroom to your sandwich. You can eat the stem if you like. Close the bun and bite into an amazing combination of flavors!

Serve with some gluten-free seasoned fries or a salad. You will be surprised how filling this is!