Cut drained tofu into small cubes. Heat 2 tb oil in a wok & fry tofu till it turns golden. Remove & marinate in soy sauce & sherry.
Cut beans into pieces 2 inch long. Heat rest of oil & stir fry beans for 1 minute. Sprinkle with salt. Add tofu & marinade. Dissolve cornstarch in water & stir into the rest of the ingredients. Cook gently till sauce thickens.
Serve hot over rice.