Heat oven to 200C/180C fan/gas 6 and put the salmon in a shallow baking dish. Mix the sweet chilli, honey, sesame oil, mirin, soy and ginger in a small bowl and pour over the salmon so the steaks are completely covered. Bake for 10 mins while you cook the pak choi.
Cut a slice across the base of the pak choi so the leaves separate. Heat the oils in a wok, add the garlic and stir-fry briefly to soften. Add the pak choi and fry until the leaves start to wilt. Pour over the stock, tightly cover the pan and allow to cook for 5 mins – you are aiming for the stems of the pak choi to be tender but still have a bit of bite.
Serve the pak choi in shallow bowls, top with the salmon steaks and spoon over the juices. Scatter with the toasted sesame seeds and serve on its own or with brown rice or noodles.