Combine salsa ingredients and set aside. In a food processor, chop mushrooms into extra fine pieces. Add beans, chiles, Worcestershire, chili powder, salt, onion powder, breadcrumbs and egg; process until fully combined. Liberally coat a large nonstick pan with cooking spray. Form 4 patties, then gently place onto pan. Grill over medium heat 5 minutes per side, or until a crisp crust forms and the burger is heated through. Place each burger into a pita half with 1/4 of the salsa and avocado slices.