An Ina Garten recipe (buy her cookbooks, they are all outstanding!). This recipe is a different take on Indonesian ginger chicken, just using swordfish instead. A great grilling recipe! Note: the prep time does not include marinating for a minimum of 4 hours, or overnight. The soy sauce acts as a tenderizer, but don't leave it on any longer then overnight or the swordfish will become mushy.
Combine the soy sauce, canola oil, lemon zest, lemon juice, ginger, garlic, and mustard in a bowl. Pour half of the sauce into a low, flat dish that is just big enough to hold the swordfish in one layer. Put the swordfish on top of the sauce and spread the remaining sauce over the tops. Cover with plastic wrap and refrigerate for at least 4 hours, or preferrably overnight.
Heat up your grill and brush the cooking grate with some oil to prevent the fish from sticking. Remove fish from the marinade, allowing some of the ginger to stick to the fish, and discard the marinade. Sprinkle the fish, on both sides, with salt and place it on the grill. Cook for about 5 minutes on each side, just until it is no longer pink in the middle. Place the fish on a platter, cover tightly with aluminum foil, and allow it to rest for about 10 minutes.