Heat oil in wok over high heat and add garlic and ginger. Cook for a few seconds then add remaining vegetables. Cook, stirring frequently, and adding a splash of sherry, when necessary to prevent sticking. Remove tofu from marinade and combine marinade with arrowroot. Mix into vegetables and stir over medium heat to thicken sauce. Lower heat to a simmer and add tofu. Cover and heat for 2-3 minutes. Serve over rice, topped with sesame seeds or chopped nuts.