SAUCE: Blend the water and cornstarch until smooth. Stir in the catsup, soy sauce, sugar, vinegar and, if desired, a few drops of hot pepper seasoning. Set aside.
PORK: Beat egg yolk with the water. Blend in 1 tablespoon flour and 1 tablespoon cornstarch until smooth. Add the cubed pork and mix to coat well. Drain off the excess mixture from the pork cubes. Place the wok over heat and add oil to 1-1/2 inch depth. Heat to 340 degrees. Use a thermometer if you can; it is more reliable than a wok with a temperature gauge. Add the drained meat and cook until golden brown, about 10-13 minutes. Remove with a slotted spoon and keep meat warm. Pour off all the oil and wipe wok with a paper towel. Return 2 tablespoons of the oil to wok. Place over medium-high heat. When oil is hot, add the garlic and green peppers. Stir-fry for about 2 minutes, or until garlic is light brown. Add the pineapple, the sauce you prepared ahead of time and the pork. Stir this mixture until it boils and thickens (about 1-1/2 minutes). Serve over steamy hot rice.