2) In a large bowl, combine the soy sauce, olive oil, garlic, ginger and sugar and mix well. Pour the marinade over the fillets and refrigerate for 4 to 6 hours.
3) Add hickory chips to the smoker following the manufacturer's instructions and preheat to 120C.
4) Place the salmon in the smoker and smoke for 60 to 90 minutes, or until the fish flakes nicely. If the fish is skinless, cook on foil.
5) Serve with freshly squeezed lemon juice.