Step 2

Cover and leave to rise until doubled, about 50–60 minutes.

Step 3

Turn the dough onto a floured surface and roll lightly to coat with flour. Roll to ½ inch thick with a floured rolling pin. Cut with a doughnut cutter. Cover and leave to rise until doubled, 30–40 minutes.

Step 4

Heat oil in a deep fryer or heavy pot to 175°C (350°F), filling it no more than a third full. Slide the doughnuts in with a wide spatula, a few at a time so the temperature holds. As they rise to the surface, flip them. Fry until golden, about 1 minute per side, then lift out and drain on paper towels.

Step 5

Make the glaze: melt the butter, remove from heat and stir in the icing sugar and vanilla until smooth. Stir in boiling water 1 tablespoon at a time until the glaze is pourable but not watery.

Step 6

Dip the warm doughnuts into the glaze and place on a wire rack to set.