Slice 2 of the onions into 1/4 inch slices. Heat 1 Tbsp oil in a frying pan. Add the sliced onion, and cook, stirring, until the outside has browned. Remove and drain. Slice the remaining onion into paper-thin slices and set aside. Rinse the bones and place in a stockpot. Cover with cold water. Bring slowly to a boil. Reduce heat and simmer, uncovered. For a clear broth skim off foam. After 10 - 15 minutes, add browned onion and ginger, carrots, cinnamon, cardamom, star anise, cloves, garlic and peppercorns. Bring to a boil. Simmer the stock, partially covered for 6 to 12 hours, skimming regularly. If necessary add more water to keep the bones covered. Strain the stock, skim off, and discard any fat. At serving time, arrange the sliced beef on a platter. Garnish with reserved white and green onion. On another platter, arrange the bean sprouts, coriander, chiles and limes. Meanwhile, plunge the rice sticks in boiling water to heat. Drain. Place equal portions in each soup bowl. Cover to keep warm. Heat beef stock to boiling. Season with fish sauce and pepper. Pour into a soup tureen or chafing dish. At the table, place the soup on a portable warmer to keep hot. Offer each guest a bowl of warm rice noodles. Each diner adds some beef and onion to a bowl. Ladle the hot stock over the meat, stirring to cook the meat. Add the bean sprouts, coriander, chiles, and lime to taste. Enjoy with chopsticks and a soup spoon. Optional: pass fresh basil leaves, coriander, additional chilies, fish sauce and ground peanuts at the table. From: kpatrucco@aol.com (KPatrucco)