Lightly crush lemongrass using the side of a knife; slice stalks into 2-inch pieces. Combine lemongrass pieces, broth, and ginger in a large saucepan; bring to a boil. Reduce heat to low, and simmer 45 minutes. Remove lemongrass pieces and ginger using a slotted spoon; discard.
Cook noodles according to package directions; drain and set aside.
Add chicken strips to broth; increase heat to medium, and cook 5 minutes. Add edamame, carrot, soy sauce, and mushrooms; cook 5 minutes or until chicken is done. Remove from heat; stir in cilantro and green onions.
Divide the rice noodles evenly among each of 5 soup bowls. Ladle chicken mixture over noodles. Garnish with lime wedges, if desired.