For the pear-porree cheese strudel, defrost the puff pastry.
Melt the butter and let it cool down a bit.
Preheat the oven to 200 °C.
Wash leek thoroughly and cut into slices.
Peel the pears, cut into quarters, remove the core and cut the fruit into cubes.
Coarsely grate cheese on a vegetable grater.
Mix leeks, pears and cheese and season with salt and pepper.
Spread puff pastry on a tea towel and brush with melted butter.
Spread the filling on the dough (leaving the edges free) and roll up the strudel.
Brush with egg yolk and bake the pear-porree cheese strudel on the middle rack for about 20 minutes until golden brown.