Preheat oven to 275 degrees F.
Rub the short ribs with salt, pepper, and the Chinese five-spice. Heat a large Dutch oven over medium-high heat and add the oil. Sear the short ribs for 6 minutes on each side, or until well browned. Remove and set aside. Carefully add the sake and mirin, scraping up any brown bits on the bottom of the pan. Reduce by about half then add the orange juice, sugar, scallions, ginger, garlic and soy sauce. Add meat back to the pan, remove from heat, cover and braise in the oven for 5 to 6 hours, or until meat is extremely tender. Remove from the liquid, cool slightly, slice and serve with lo mein noodles or stir-fried vegetables, if desired.