Freeze pork slightly, and cut into long thin shreds. Mix with baking soda and water. Cover, and let sit (unrefrigerated) for 5 hours. When ready to cook, rinse pork and dry well.
Prepare the sauce by mixing together tomato puree, vinegar, chili paste, water, sugar, Shoa Hsing, soy sauce, sesame oil, MSG, and cornstarch paste. Soak the tree ears in 1 cup of boiling water for 15 minutes and remove.
Heat 4 cups of peanut oil in a wok to 375 degrees F. Add rinsed and dried pork, and deep fry for 30 seconds. Remove pork and place on paper towels. Let the oil return to 375 degrees and add shredded celery. Deep fry for 30 seconds. Remove and place on paper towels. Pour off all but 1 tablespoon oil.
Over high heat, stir fry garlic, ginger, and scallions for 1 minute. Add water chestnuts. Stir. Add pork, celery, and tree ears. Stir. Add sauce mixture. Bring to boil quickly and serve (approximately 15 seconds).
*Available at Asian groceries
Chinese dark vinegar is a brownish-black vinegar and has a very full flavor. The best substitute is balsamic vinegar from Italy.