Place salmon fillet in a ziplock bag. Combine the olive oil, balsamic vinegar and soy sauce. Put in bag with salmon fillets. Marinade for 20-30 minutes.
Preheat oven to 350 degrees. Place salmon on a foil lined baking sheet and bake 15-20 minutes, basting with marinade halfway through. Put remaining marinade in a pot and cook over medium high heat to a boil. Simmer for for 3-5 minutes stirring till reduced. Serve sauce over salmon. Enjoy.