In a large bowl, whisk together all the ingredients to form the marinade
Place the salmon in a gallon size Ziplock bag, then pour in the marinade. Remove most of the air from the bag before sealing it. Allow the salmon to marinade for at least 10 hours.
Preheat the oven to 425F degrees.
Make an aluminum foil packet for each filet and pour in 4 tablespoons of marinade before sealing the packets.
Bake for 20 minutes on a cookie sheet.
Plate the salmon and pour the leftover marinade in the foil packets over the filets, then serve.
Notes
Add 3 minutes to the baking time for each additional filet.
Recipe by Sprig and Flours at http://www.sprigandflours.com/baked-salmon-with-a-sweet-soy-sauce-marinade/