Remove the scallops from their shells or ask your fishmonger to do this. Separate the white flesh from the corals, and detach the hard skin round the whites and the tiny black sac from the coral. Wash clean under a running tap. Halve the whites horizontally. Leave to dry off on some paper towel.
Wash the leeks and discard the green parts (you can use them for soup or stock). Slice the w