Clean the leek and cut into 8 even pieces. Bring the water with salt to a boil. Cook the leek in it for 10 minutes, drain and allow to cool. Wrap 1 slice of ham and Gouda cheese around a piece of leek and place on top of the puff pastry. Spread the egg white on the edges of the puff pastry and press down well. Place on a baking sheet rinsed with cold water. Whisk the egg yolks and brush the puff pastry pieces with it. Let rest for 15 minutes.
Bake in the hot oven at 200 ° C top / bottom heat on the middle rack for approx. 20 - 30 minutes.
Serving: Put the ham-leek in the puff pastry on the plate and serve with the salad.
Tip: A spicy sauce, e.g. spicy cucumber cream, goes very well with this dish