Steamed mussels are served in the shell with a dollop of Chef Nobuyuki Matsuhisa's special onion salsa.
Pulse the onions in a food processor until finely chopped. Transfer the onions to a strainer over the sink, and lightly press down on the onions with a rubber spatula to release any excess juices; set aside.
In a medium mixing bowl, whisk together the minced garlic, ginger, chile-garlic paste, vinegar, grapeseed oil, chile-garlic oil, soy sauce, and 1 teaspoon salt. Stir in the onions and parsley. Cover, and transfer to the refrigerator to chill overnight.
Let the salsa come to room temperature. Steam the mussels until they just open. Add just enough water to 1 cup of coarse salt to make a thick paste. Place one mussel on top of a small mound of salt to keep it balanced, and spoon a tablespoon of salsa into each of the open mussels, and serve.