Add the chicken broth, lemongrass stalks, grated ginger, lemon zest, lemon juice, bay leaf, and bring to a boil.
Add the orzo and cook, stirring occasionally, for 8 minutes, or until orzo is tender. Add the chicken and the carrots and heat for about 5 minutes.
Remove pot from heat. Discard the bay leaf and lemongrass stalks and stir in the parsley. Check for seasonings, add salt and pepper, to taste. Serve warm.
Notes
Substitute shredded rotisserie chicken in the soup for a quicker meal.