Place cubed pork and flour together in a resealable plastic bag. Seal and shake. Meanwhile, heat oil in a large skillet or wok. When hot, add coated pork and brown quickly; remove with a slotted spoon and set aside. Pour off the remaining oil.
In the same skillet combine the chicken broth, water, soy sauce, and sherry. Stir together and add the green onion, garlic, sugar, ginger, salt, pepper, and reserved pork cubes. Bring all to a boil. Then lower heat, cover, and let simmer for 15 minutes or until pork is tender. Check occasionally to make sure sauce is not thickening too much. If needed, add more water.