Set large, flameproof casserole or stockpot over medium heat; add oil. A minute later, add garlic and chopped onion. Cook, stirring occasionally, until softened, about 5 minutes. Meanwhile, combine pork and minced onion with a large pinch of salt; form into about 20 small meatballs.
When onion is cooked, remove with slotted spoon. Add meatballs to pan. Turn heat to high; brown quickly, about 5 minutes. Return onion to the pan along with the stock, anise, pepper, cloves, cinnamon, ginger, nam pla and sugar.
Bring to a boil, then lower heat and simmer, uncovered, for about 20 minutes, until the meatballs are cooked through and the seasonings have married.
Meanwhile, cook the rice noodles in boiling salted water until tender, just a few minutes. Strain, rinse in cold water, and set aside.
When meatballs are cooked, add noodles to the broth and reheat them. Divide noodles and meatballs among 6 - 8 serving bowls and pour in the broth. Garnish with bean sprouts, cilantro, basil, chiles and scallions. Serve, squeezing lime juice over all.