Divide the strawberries among 4 shallow 300 ml (½ pint) ovenproof dishes, or use a large 1.2 litre (2 pint) dish if preferred.
Put the egg yolks, sugar and 4 tablespoons of the sherry in a large bowl and set over a pan of simmering water. Cook the mixture, whisking continuously using a hand-held electric whisk (or rotary hand or balloon whisk), for 5 minutes until the mixture is very thick and frothy and almost half-fills the bowl.
Add the remaining sherry and cook for a few more minutes until thick once more. Pour the mixture over the strawberries and sift the icing sugar over the top.
Cook under a preheated hot grill for 3–4 minutes until golden or caramelize the sugar with a cook's blowtorch. Serve immediately.