Snap off the tough ends of the asparagus, then cut the spears into 3 pieces. Blanch them in salted boiling for 1 minute, then drain them, slice each piece lengthways and leave to cool down.
Cut each avocado in half, remove the stones, then peel and slice them.
Place the rye bread slices on a work top and spread the butter evenly on each slice. Place the asparagus on the bread, then the avocado slices.
Poach the eggs, according to your preferred method. Place an egg on top of each sandwich. Sprinkle with Aleppo pepper and decorate with cress or chervil. Serves 4.