Monkfish with Cucumber and Tomato Hollandaise

• 675 g/1½ lbs monkfish tail cut into 1 cm/½ inch collops

First make the sauce. Put the egg yolks in a heavy stainless steel saucepan on a very low heat, or in a bowl over hot water. Add water and whisk thoroughly. Add the butter bit by bit, whisking all the time. As soon as one piece melts, add the next piece. The mixture will gradually thicken, but if it shows signs of becoming too thick or slightly ‘scrambling’, remove from the heat immediately and