Heat 1 teaspoon oil in large non-stick skillet. Add mushrooms, carrots, onions and zucchini; cook over medium-high heat 5 minutes or until vegetables are tender. Transfer vegetables to food processor bowl. Add oats, beans, rice, soy sauce, garlic, pepper, and cilantro if desired. Pulse for about 20 seconds or until well blended. Divide into eight 1/2-cup portions. Shape into patties between waxed paper. Refrigerate at least 1 hour or until firm. Heat remaining 2 teaspoons oil in same skillet over medium-high heat. Cook patties 3 to 4 minutes on each side or until golden brown. Serve on buns with toppings, if desired.