While noodles are soaking, cut chicken into thin julienne strips. Heat
oil in deep skillet over medium-high heat; add chicken; garlic, ginger,
and pepper flakes. Cook, stirring for 1 minute; then add broth and fish
sauce and bring to a boil.
Reduce heat to medium
and simmer until chicken is done, about 8 minutes.
Drain noodles and
cut into short pieces, about 1-1 1/2 inches long. Arrange noodles in bottom
of bowls; ladle soup over the top and sprinkle with cilantro, onion, and