Take off the skin from the salmon filet and wash it with cold water. Dry the salmon filet and cut into 1/2 inch cubes, or smaller or larger depending on your preferences.
To make the marinade, in a large mixing bowl, combine the soy sauce, sesame oil, brown sugar, ginger, white onion, and green onions and mix well. Add in the salmon cubes into the marinade bowl and let marinate in the fridge for at least 30 minutes.
Eat as a salad or serve on top of a bowl of rice. Top with some lemon juice, seaweed salad and some sesame seeds.