Grilled Mackerel with Sweet Soy Glaze

Score the mackerel fillets a couple of times on the skin, then lay them in a shallow dish. Sprinkle with the lime zest and juice, and leave to marinate for 5-10 mins.
Place all of the sauce ingredients in a small pan with a splash of water and gradually bring to a simmer. Cook for 5 mins to thicken slightly, then remove from the heat and set aside.
Turn the grill to its highest setting and place the mackerel on a greased baking tray, skin side up.
Sprinkle the fillets with the olive oil and some sea salt, then grill for 5 mins until the flesh is opaque and cooked through.
Divide bok choi between plates, lay 2 mackerel fillets on top, drizzle with the sauce and serve with a wedge of lime.