Place pork, sherry, and ginger slice in pot . Cut 1 of the green onions in half crosswise and add to pork, then add enough water to barely cover meat. Cover and simmer until meat is tender when pierced (about 35 minutes).
Lift meat from broth and refrigerate until cold. Then cut into 1 ½ inch square pieces about 1/8 inch thick. Dispose of broth or use it for another recipe.
In a bowl combine the hoisin sauce, pepper flakes, soy, and sugar. Seed bell peppers and cut into 1-inch squares: cut remaining 5 green onions into 1-inch lengths.
Place wok over high heat: when wok is hot, add 2 tablespoons of oil. When oil is hot,
Add bell peppers and stir fry for 1 ½ minutes, adding a few drops of water if wok appears dry. Sprinkle with salt and stir once, then remove peppers from wok. Add remaining 1 tablespoon oil to wok. When oil begins to heat, add garlic and minced ginger and stir once; then add pork and stir-fry for 1 minute until cooked through. Add hoisin sauce mixture and toss until pork is coated with sauce. Return bell peppers to wok along with onions. Stir for 30 seconds to heat thorough. Serve with white rice.