Preheat the oven to 220C/425F/Gas 7.
To make the dough, place all the ingredients into a large bowl, holding back a quarter of the water. Stir the mixture with your hands, then slowly add the remaining water to form a dough and knead in the bowl for four minutes.
Turn the dough onto a lightly floured surface and knead well for 10 minutes or until the dough is smooth and elastic. Return the dough to the bowl, cover with a damp tea towel and leave to rise in a warm place for one hour.
Divide the dough into 12 pieces, each about 70g/2½oz, then roll into balls and shape into fingers about 13cm/5in long.
Place the dough fingers onto a greased baking tray, leaving space for them to double in size, then set aside in a warm place for 40 minutes. They should just touch each other when they’ve risen. Bake in the oven for 10 minutes then set them aside to cool.
For the icing, sift the icing sugar in a wide bowl and gradually stir in the cold water to form a thick paste.
Dip the top of the cooled fingers into the icing, smoothing it with your finger, then leave to set on a wire rack.
Lightly whip the cream and spoon it into a piping bag fitted with a small nozzle. Spoon the strawberry jam into another piping bag.
Sliced the iced fingers horizontally, leaving one long edge intact. Pipe in a generous line of whipped cream into the middle of each finger, then a thinner line of jam. Dust the iced fingers with icing sugar and serve.