01 - Preheat oven to 400°F (200°C). Line a baking tray with parchment paper or lightly grease with oil.
02 - In a small saucepan, combine soy sauce, mirin, honey, brown sugar, rice vinegar, minced garlic, grated ginger, and sesame oil. Bring to a gentle simmer over medium heat, stirring until sugar is dissolved and the sauce thickens slightly, about 3 to 4 minutes. Remove from heat and allow to cool for 2 minutes.
03 - Arrange salmon fillets evenly on the prepared tray. Brush half of the teriyaki sauce over the fillets, coating them thoroughly.
04 - Place tray in the center of the oven and bake for 12 to 15 minutes, or until the salmon is just cooked through and flakes easily with a fork.
05 - Brush the remaining teriyaki sauce over the baked salmon. Sprinkle with sesame seeds and sliced spring onions before serving.