Unroll the puff pastry on the worktop and cut it into long, narrow triangles running across the short side of the sheet. The wide end of each croissant should measure 5-6 cm. See the video above the recipe.
Roll the triangles up into croissants, from the wide end towards the narrow tip. Place the croissants seam-side down on a baking tray and brush them with the beaten egg.
Bake in a preheated conventional oven (top and bottom heat) at 200°C for about 15-20 minutes, or until golden.
Let them cool slightly, then cut or snip the croissants open.
Spread them with cream cheese and fill with crisp lettuce, salmon and avocado. Season with salt and freshly ground pepper and serve.