ADD TO LARGE POT of boiling water: bacon or pork belly, scallions, ginger, salt. Cover tightly; simmer for 1 1/2 hours. Remove meat with slotted spoon and drain well. Discard liquid. When bacon or pork belly has cooled, cut it into thin 1/4-inch slices. Cut scallions into 3-inch pieces. Heat wok or large saute pan until hot. Add oil and pork and stir-fry for 10 minutes. Drain any excess oil. Add garlic and ginger; stir-fry 10 seconds. Add scallions and stir-fry 3 minutes. Add the other ingredients; stir-fry 3 minutes, mixing well. Serve at once.