To make sauce: Soak the beans in water overnight, rinse and drain. Combine black beans, stock, ginger, garlic, chile and vinegar in a saucepan and bring to a boil over high heat. Reduce heat and simmer, covered, until beans are tender, about 1 hour. Pour into blender or food processor, add the salt and blend until smooth. Return to the saucepan and hold over a low heat. To make stir-fry: Trim all the fat from meat and cut, against the grain, into quarter-inch strips. Place oil in a nonstick skillet or wok over high heat. Add the meat and stir fry for a few seconds. Add ginger, garlic, celery, mushrooms and onion; stir fry until vegetables are tender-crisp. Add sprouts and and a cup of the sauce, cover and cook a further 30-40 seconds and remove from heat. Serve with steamed rice and pass the rest of the sauce at the table. Jim Weller