Cook onions, carrots and mushrooms in EVOO until tender. Stir in sriracha, oregano and salt. Add 1/2 of the black beans to a bowl and mash. Mix in panko, the remaining beans, the vegetable mixture and egg. Shape into patties. Bake on a greased baking sheet at 450 degrees until crisp, about 15 minutes. Serve on buns with your favorite toppings.