Baby Portabella Burger Ingredients Mini Pretzel Rolls Medium Portabella Mushrooms Salt & Pepper, to taste Olive oil for brushing the mushrooms Sprouts or mixed field greens Tomato Slices Red Onion, sliced thin Vegan Swiss Cheese Slices For the Sriracha-Style Mayo: Vegan Mayonnaise 1 Tbl Tabasco 1 tsp Lemon Juice ¼ tsp Soy Sauce Paprika, to