01 - Preheat oven to 400°F. Line a baking tray with parchment paper or lightly grease it.
02 - In a small saucepan, combine soy sauce, mirin, honey, brown sugar, rice vinegar, garlic, ginger, and sesame oil. Bring gently to a simmer over medium heat, stirring until the sugar dissolves and the sauce thickens slightly, about 3–4 minutes. Remove from heat and let the sauce cool for 2 minutes.
03 - Arrange salmon fillets on the prepared tray. Brush half of the teriyaki sauce evenly over the fillets to fully coat.
04 - Bake in the center of the oven for 12–15 minutes, or until the salmon is just cooked through and flakes easily with a fork.
05 - Brush the hot salmon with the remaining teriyaki sauce. Sprinkle with sesame seeds and spring onions just before serving.