Mix together the pork, the egg, 1 tablespoon of the cornstarch, the five-spice powder, 1 tablespoon of the scallions, 1/2 teaspoon of the sugar, 1/4 teaspoon of the sesame oil, and 1/4 teaspoon salt. Place the vegetable oil in a hot wok over very high heat, then add small clumps of the pork mixture. Stir-fry for about 1 minute, or until the clumps are browned and cooked through. Remove from wok and reserve.
Lower the heat to medium. Add to the wok, 6 tablespoons of scallions, the minced red pepper, the minced green chile, the minced garlic, and the minced ginger root. Stir-fry for 30 seconds. Add the browned pork and stir well, tossing with the remaining 2 1/2 teaspoons of sugar. Turn heat high and add the chicken stock, soy sauce and oyster sauce. Stir well and bring to a boil. Mix the remaining 2 teaspoons of cornstarch with a little cold water in a cup, then stir into the wok. Gently stir in the bean curd cubes, taking care not to break them up.
Remove from wok and place on serving platter. Sprinkle with the remaining half-teaspoon of sesame oil.