Cornstarch paste Preparation: In saucepan, cover pork butt with water, bring to a boil & simmer for 30 minutes. Add more hot water if level goes below pork. Cool pork in its cooking water. Wash, then soak mushrooms in warm water for 1 hour. Squeeze liquid from mushrooms, reserving liquid. Discard mushroom stems, and halve mushrooms. Halve, seed & core bell pepper; cut into pieces about 1" by 1 1/2". Slice bamboo to match bell pepper. Peel carrot; slice on bias into ovals. Remove pork from cooking water, & parboil carrots in water for 1 minute. Slice 2/3 of pork butt into rectangles same size as bell pepper. Save remaining 1/3 for another dish. Strain mushroom liquid; combine specified amount with soy sauce, sugar & salt. Drain bean curd, rinse in cold water, and slice same size as bell pepper. Stir-fry: Add oil to very hot wok. When oil begins to smoke, stir-fry mushrooms, garlic and ginger for 1 minute. Add bell pepper, bamboo shoots, carrots & pork; stir-fry for 1 minute. Add bean curd & mushroom liquid; bring to boil. On medium heat, cover wok & cook for 1-2 minutes, until bell pepper is bright green & crisp. Push ingredients up side of wok. Restir thick cornstarch paste, then dribble into liquid until it thickens; cook briefly while stirring. Recombine with ingredients. Serve.