Bring 4 cups water, celery, onion, soy sauce, onion powder, garlic powder, and pepper to a boil in a pot over medium heat. Reduce heat to medium and simmer 5 minutes. Stir in oats, mushrooms and flour and cook 5 minutes more. Transfer to a bowl and chill.
Preheat oven to 350°F; coat baking sheet with cooking spray. Shape mixture into patties and bake on prepared baking sheet for 15 minutes. Flip and bake 10 more minutes. Cool.
Heat grill to medium-high. place foil on grill and coat with cooking spray. Grill burgers on foil for 7 minutes per side. Serve.
Red Pepper Ailoi:
Puree all ingredients in blender until smooth. Season with salt and pepper.