Mix salmon fillet, soy sauce, ginger, sugar in a pan and fill it with water until it slightly cover the salmon. Marinade the salmon for about 2 hours. Discard the marinade. Prepare the smoker and smoked the salmon fillet for 1.5-2 hours on low heat. Take the salmon out, let it cool until it reaches room temperature. Shred/brake the fillet to small pieces by hand or a fork. Mix the remaining ingredients into salmon fillets. (The consistency should be like tuna salad in tuna sandwiches. If the mixture is too dry, you can add extra mayo) Serve it with crackers or baguette or celery or endives.