For the apple strudel, first make the dough. To do this, knead all the ingredients until you get a silky smooth dough. Let rest for half an hour covered with a wet tea towel.
For the filling, peel the apples and cut them into narrow wedges. Drizzle with juice of one lemon to prevent them from turning brown.
Dust the strudel cloth well with flour and roll out the dough into a rectangle. Carefully flatten the dough by hand into a very thin, translucent, but not holey, square. Now brush the dough with the melted butter and place the peeled apple slices on two thirds. Mix the raisins, sugar, cinnamon and rum and sprinkle on top.
Trim the edges of the dough and roll up the strudel with the help of the cloth. Place the rolled strudel on a greased or paper-lined baking tray, brush with melted butter and bake in the oven at 180 °C for about 40 minutes.
Remove the apple strudel and sprinkle with powdered sugar.