Preheat your oven to 200°C (400°F). While it heats, line a 9x13 inch baking dish with a large sheet of aluminium foil, leaving enough overhang to fold into a parcel later. This isn't just for easy cleanup — the foil parcel traps steam to keep the salmon incredibly moist.

Make the teriyaki sauce. In a small mixing bowl, whisk together the soy sauce, honey, rice vinegar, sesame oil, grated garlic, and grated ginger. The mixture should look dark amber and smell pungently sweet and savoury. Give it a taste — you want a balance of salty and sweet, with a gentle kick from the ginger.

Place the salmon fillets in the lined baking dish, skin-side down if you've kept the skin on. Pour the teriyaki sauce over the fillets, turning them gently to coat each piece. The salmon should be glistening and evenly covered in the dark sauce. Let it sit for 5 minutes while the oven finishes preheating — this quick marinade is enough to infuse flavour.

Fold the foil over the salmon to create a sealed parcel, crimping the edges tightly. Place the dish in the oven and bake for 12 minutes. During this time, the salmon will steam inside the parcel, turning from translucent orange to a delicate opaque pink. You'll smell the sweet aroma of the sauce mingling with the fish.

After 12 minutes, carefully open the foil parcel (mind the steam — it's hot!). Spoon the pan juices over the fillets, then return the dish to the oven, uncovered, for another 3-5 minutes. Watch closely: the sauce will begin to bubble and thicken, turning glossy and sticky around the edges of the fish. The surface of the salmon should look caramelised and slightly darker at the edges.

Test for doneness. The salmon is ready when it flakes easily with a fork and the internal temperature reaches 63°C (145°F) at the thickest part. The flesh should look uniformly opaque, not translucent in the centre. If you see any resistance when flaking, give it another minute.

Let the salmon rest for 2 minutes in the baking dish. This short rest allows the juices to redistribute, ensuring every bite is moist. Meanwhile, spoon the thickened teriyaki glaze from the dish over the fillets. Sprinkle with sesame seeds and sliced spring onions for a fresh, crunchy finish.