Preheat oven to 400 degrees F and line large baking sheet with unbleached parchment paper or silicone baking mat.
In a small bowl, whisk brown sugar, soy sauce, oil, vinegar, garlic and ginger. Make sure sugar dissolves completely. Divide marinade into 2 bowls – 2/3 and 1/3 of it.
Place salmon skin side down on prepared baking sheet and brush with 1/3rd of marinade.
Bake for 15 minutes for wild salmon or thin farmed salmon slices, and for 20 minutes for farmed salmon and thicker/wider slices. Check with a fork after 15 minutes - if salmon flakes easily, it is done. Do not overcook!
While salmon is cooking, add 2/3 marinade to a small pot with and cook for a few minutes, until thickened and bubbly. You can always add 1 tbsp extra brown sugar in case you “lost” some undissolved sugar for brushing uncooked salmon.
Remove salmon from the oven, brush with teriyaki glaze, sprinkle with green onion and sesame seeds.
Store: Refrigerate leftovers for up to 5 days in an airtight container.
Reheat: Preheat non-stick skillet and add a splash of water. Place salmon skin side down, cover and simmer on low heat until warmed through. Or use microwave.
Don't over cook: Farmed salmon is more fatty and is harder to overbake. Where as wild salmon can come out dry and is easy to overbake.
Skin: You can keep skin on, especially on wild salmon, to help it retain more moisture. Remove after baking.