1. Blend all the sauce ingredients together and place in a small serving bowl or ramekin.
2. If using fresh scallops, loosen from the shell and trim away any chewy muscle, if necessary. Rinse to remove any grit and return to the shells. Season lightly with salt and pepper and top with a few shreds of ginger.
3. Steam in the shells for about 6 minutes: do this in 2 batches if the scallops are large; if small, steam 2 scallops per shell; if frozen, steam in small ramekins.
4. Remove the shells carefully from the steamer to keep all the juices and arrange on a serving plate with the sauce bowl in the centre. Garnish with spring onion shreds.
5. Each diner should spoon sauce onto the scallops before eating, then drink the juice afterwards.