Then add the lemongrass, lime juice, fish sauce and coconut milk. Bring to a simmer and cook for 10 minutes at a simmer.
While the broth is simmering, use a pair of scissors or a knife to cut the rice noodles into 2-3" pieces.
Remove the broth from the heat and add seafood. Cover and let sit for 15-20 minutes, until seafood is cooked through.
Add cut, cooked rice noodles and tofu to a bowl. Ladle the soup into the bowl and garnish with bean sprouts, limes, fresh mint and fried shallots.