1. Bring first 9 ingredients to a simmer in a medium saucepan; keep warm.
2. Bring 6 cups water to a boil in a large saucepan. Add rice noodles; cook 3 minutes. Drain. Place about 1/4 cup rice noodles in each of 4 bowls.
3. Discard ginger. Add juice to broth mixture; stir. Ladle 1 1/3 cups broth mixture over each serving; top with 1 tablespoon each mint, cilantro, and green onions.