For the hollandaise, place the egg yolk, lemon juice and a little salt in a tall mixing bowl and blend until smooth with a hand blender. Melt the butter. While the hand blender is running, slowly pour into the egg yolk mix.
Season with salt and pepper. Stir in crème fraiche. Warm up the hollandaise (do not boil!) and keep warm.
Bring 1 1/2-2 l water to the boil in a wide saucepan. In the meantime, cut toasties in half and toast. Put 1 slice of ham on each half of the toastie.
Pour vinegar into boiling water. Poach the eggs in it, lift them out and let them drain. Put 1 poached egg and some hollandaise sauce on each toastie. Serve sprinkled with coarse pepper.