Puff pastry strudel with ham, potato and mozzarella

I cook the potato: I washed it, wrapped in microwave-safe cling film and microwaved for 10 minutes, or boil as usual.
I slice about 1 cm thick and cool.I slice the mozzarella and dry on kitchen paper to remove liquid that could make the pastry wet.I prepare the ham.I lay out the rectangular pastry.I arrange ham lengthways, overlapping 2 slices.I add potato slices.I top with mozzarella and a pinch of salt and pepper.I fold the ham over itself.I wrap it in pastry, leaving the upper part free.I turn it and make regular cuts along the pastry with a knife.I beat an egg with a fork.I brush the roll.I wrap the pastry strips around the strudel.I brush again.I scatter alternating poppy and sesame seeds over the strips.I bake at 180°C for 20 minutes.I let cool slightly before slicing.