Bring broth, rice, lemongrass and galangal to a boil and simmer, covered, until rice is cooked about 10-15 minutes. Add raw chicken pieces, if using, until cooked through. If using pre-cooked chicken, add in the last minute to heat up.
While rice is cooking in broth, fry the garlic and shallots or onions in oil and set aside.
Ladle soup into individual bowls and add additional seasonings, in any amount and in any combination you prefer, to taste.