Steamed Bass with Onion, Ginger and Scallion

Steamed Bass with Onion, Ginger and Scallion 1 1½-pound whole white fish (such as black sea bass, branzino, or flounder), cleaned with head and tail intactKosher salt and freshly ground black pepperfreshly ground black pepper2 by ½-inch piece fresh ginger (peeled and...