(For best results, soak your clams in a cool freshwater bath for 20 minutes prior to cooking).
Rinse and clean your clams. Discard any clams that are broken or are already open. Set aside.
In a pot or dutch oven, melt the butter over medium heat. Add the garlic and ginger and cook about two minutes, until fragrant. Stir in the curry and cook another 2 minutes, followed by the fish sauce, chicken broth, and coconut milk. Bring to a simmer, lower the heat, pour in the clams, and cover. Steam the clams for 5-7 minutes until they all pop open (if there are some still unopened after 7 minutes, discard them). Remove from heat. Stir in cilantro, the juice from 1 lime wedge and season with salt to taste. Serve with additional lime wedges and steamed rice or crusty bread.