In a non-reactive bowl, combine the soy sauce, pineapple juice, sherry, brown sugar, ginger and lemon juice.
Place in heavy plastic bag with swordfish steaks and refrigerate for 1 to 2 hours, turning bag occasionally to thoroughly marinate all surfaces of the fish.
Remove swordfish from bag and frill over high heat, 4-5 minutes on each side, turning once.
Be careful not to overcook swordfish; it dries out quickly (fish is done when flesh is opaque and flakes easily with fork.)
Serve with lightly grilled slices of pineapple and baked sweet potatoes.