1. In sealable plastic bag combine well the soy sauce, garlic, lemon juice, and sugar. Add salmon, coating it well. Let marinade, sealed and chilled, for 30 minutes.
2. Remove the salmon from the bag, discard the marinade, pat it dry.
3. Press 2 teaspoons of pepper onto each piece of salmon, coating it thoroughly.
4. In a heavy skillet heat the oil over moderately high heat until it is hot but not smoking. Saute salmon for 2 minutes on each side, or until it flakes. Transfer the salmon with a slotted spatula to paper towels and let it drain for 30 seconds.