Mix the flour, egg white, oil, milk and salt in a bowl, kneading to give a soft, elastic, smooth dough.
Put to rest in a cool place, covered with a damp cloth.
Meanwhile, prepare the rich filling: peel the apples, core and sprinkle with lemon juice.
Melt the butter in a frying pan and brown the breadcrumbs. Add the jam, raisins, pine nuts, breadcrumbs, grappa and cinnamon to the apples.
Roll out the pastry very thinly with a rolling pin, then place a strip of the apple mixture down the centre. Fold the pastry over and seal the strudel. Use your fingers or, even better, a pastry brush, to wipe the top of the strudel with the egg white mixed with a pinch of sugar.