Place 1 tbsp wholegrain mustard, the tamarind paste and honey in a dish. Peel and grate in the garlic. Pare a few strips off the orange and set them aside for later, then squeeze in the juice from half the orange. Add a pinch of salt and stir the tamarind glaze ingredients together to make a smooth sauce.
Add the cod fillets to the dish and turn a few times to coat in the marinade. Set aside to soak while you prepare the rice.
Trim the roots and top 1cm off the spring onions then finely slice them, both the white and green parts. Keep some of the green parts separate for later. Halve the chilli. Crumble the coconut cream.
Warm a small pan over a low heat for 2 mins, then add the spring onions with ½ tbsp oil and a pinch of salt. Gently fry for 3-4 mins, stirring a few times, till the onions are soft and glossy looking.
Stir in the crumbled coconut cream and add the chilli halves to the pan. Tip in the rice and stir to mix, then pour in 400ml boiling water. Pop on a lid and turn up the heat. Once the rice is boiling, turn the heat right down and gently simmer for 12-15 mins, till the rice has absorbed all the water and is tender and sticky.
While the rice is cooking, heat your grill to high. Line a baking tray or grill pan with foil. Lift the cod out of the marinade and lay it on the tray, skin-side up (keep the rest of the marinade). Slide the tray under the grill and cook for 6 mins.
Quarter the bok choi and brush each wedge with ¼ tsp oil. Take the cod out from under the grill. Thickly brush it with some of the leftover marinade. Lay the bok choi on the tray around the cod. Grill for 6-7 more mins till the cod is cooked through – it will be opaque, white and flake easily when pressed with a fork. The bok choi will char and wilt a little.
Fluff the rice up with a fork and fish out the chilli halves. Scoop the rice onto 2 warm plates. Top with a cod fillet and 2 bok choi quarters each. Serve straight away, garnished with the last of the spring onion greens and the orange zest.