Preheat oven to 350F. Grease cookie sheet or line with parchment paper and set aside. Place tofu in food processor and pulse until coarsely crumbled. Transfer to a large mixing bowl. Process celery, onion, mushrooms and bread as you did the tofu. Add spices and mayo, stirring to thoroughly combine. Scoop mixture with a 1/2 cup measuring cup, packing it in tightly to form a cake. Turn out on cookie sheet and bake 30 to 40 minutes or until golden brown.
Chef's Note: I like to serve these cakes with the Thousand Island Dressing from Skinny Bitch in the Kitch, using fat-free vegan mayo and adding a generous amount of Old Bay Seasoning and hot sauce.