Champagne sabayon with fresh berries

Start it only just before serving: it takes about 10 minutes and is served as soon as it is ready.

Set a pan with a little water on the stove for a bain-marie and keep the water barely simmering, not hot.

Off the heat, mix the egg yolks with the sugar in the bowl, then add the champagne and the lemon.

Whisk off the heat for one or two minutes first to dissolve the sugar -- a very liquid mixture climbs the sides too fast otherwise.

Set the bowl over the barely simmering water and warm the mixture, whisking hard and without stopping, so the eggs part-cook and it foams to double or triple its volume.

At three minutes the foam is growing and thickening.

At five minutes it is all foam; from here the champagne reduces, the egg cooks and the stiffness starts, so watch it closely and do not overcook it.

At ten minutes it is done -- the side of the bowl starts to dry up. Take it straight off the heat and put it down on the side so it stops cooking.

Test the consistency: it should coat the back of a spoon and stay foamy. Remove the piece of lemon.

Scatter raspberries and blueberries in the dish and pour the sabayon over them immediately, covering them but not drowning them -- it is very sweet.

Brulee patterns into the surface with a chef torch rather than an oven broiler, which heats the whole dish and burns things.