Place blue-eye fillets in a large, shallow, heatproof bowl that will fit inside a large bamboo or metal steamer. Mix all marinade ingredients with 2 tbsp water and pour over fish. Place the bowl in the steamer and cover with a lid.
Fill a large pot with water and bring to a boil. Place the steamer on top.
Steam for about 5-10 minutes or until fish is just cooked, then remove steamer and set aside to rest, with fish still inside the steamer tray.
With the water still boiling, blanch the bok choy for a minute or two. Drain well. Share the bok choy over four plates.
Carefully lift the fish out of the steamer and sit each fillet next to the bok choy. Spoon over some of the sauce from the bottom of the steaming bowl. Add a pinch of white pepper on each fillet and garnish with spring onions and coriander. Serve immediately.