In a pot, bring the chicken or vegetable broth to a boil.
Add the lemongrass, kaffir lime leaves, and galangal to the pot.
Let the broth simmer for about 5 minutes to infuse the flavors.
Add the sliced mushrooms and cook for another 3 minutes.
Stir in the bird's eye chilies for heat.
Add the shrimp and cook until they turn pink, about 2-3 minutes.
Season with fish sauce and lime juice, adjusting to taste.
Remove from heat and discard the lemongrass and lime leaves if desired.
Serve hot, garnished with fresh cilantro.