If using dried mushrooms, soften in hot water for 20 minutes and drain. Blanch the carrot and set aside. Soak the mussels or clams for 5 minutes in 4 cups (1 liter) of cold water mixed with 2 tablespoons of salt. Rinse the seafood under cold running water and drain. Blanch the shirataki noodles for 2 minutes, drain and when cool enough to handle, cut into 4-in (10