Place the dried tree ear mushrooms in a mixing bowl covered with boiling water. Soak them for 20 to 30 minutes, drain, squeeze dry, and slice, throwing out the hard clumps.
While the mushrooms are soaking, add two cups of water to the saucepan with the sugar, vinegar, salt, and soy sauce. Bring to a boil and stir until sugar dissolves.
Heat two tablespoons of oil in a wok and add the green peppers and onions. Saute until the onions are translucent, and add the shitake mushrooms, tree ear mushrooms, bamboo shoots, and garlic. Cook for five minutes, stirring.
Mix the cornstarch with the remaining 1/4 cup of water and stir into the simmering sauce. Increase the heat while constantly stirring. As it starts to boil, it will become thicker.
Add the pineapple and bean sprouts to the vegetables and stir for one minute.
Add the sweet sour sauce to the vegetables, and mix well. The sauce should be thickened.
Heat the cooked won tons in the oven at 350 until warm. Place the desired number of won tons on each plate and add the sauce.
Serve with rice.