Heat oven to 100°C.
Peel the potatoes and cut them into chunks of the same size. Simmer in salted water until tender. Drain off the water and return the chunks to the saucepan. Cover it and allow to steam for 10 more minutes.
Add the 6 tblsp butter, salt and pepper, and mash the potatoes until smooth. Mix 60g of flour through the mash until sticky but pliable. If it is still too sticky, add a bit more flour. Keep the dough in a warm oven as it is easier to handle when warm.
Heat up a frying pan on medium heat and add the oil. Turn the mash mixture onto a work surface and knead for a minute. If it is still too sticky, add more flour. Divide the dough into 8 portions.
Flatten each of the potato portions with your hands to a thickness of about 0.6 cm (1/4 inch), and fry until both sides are golden brown. Transfer the potato cakes to a plate in the warm oven to keep them warm.
Prepare a bowl of ice water and set aside. To blanch the asparagus, boil salt water in a large pot and add the asparagus for 2 minutes, then take the asparagus out of the hot water and immediately transfer them into the ice water. Drain the asparagus and set aside. Flake the salmon.
Bring a large pot filled half with water to a simmer. Add the tablespoon of vinegar to the water. Chop the herbs. Melt the butter and skim the white milk solids off the top to make clarified butter, and fill it into a small glass or porcelain jug (for example a measuring cup).
Add the egg yolks and lemon juice to a stainless-steel bowl which you then place over the pot with the simmering water. Start whisking until the egg yolk mix is pale and slightly thick (abt. two minutes). Start adding the clarified butter to the mix in a very slow, thin stream, and keep whisking the entire time.
Keep adding the butter until the mixture thickens to a pale yellow and a thick consistency that can still be poured. You might need less than the prepared amount of butter.
Sprinkle the fresh herbs into the sauce and season to taste. Poach the eggs in the simmering water for about 3 minutes. Reheat the asparagus in the hot frying pan.
Place two hot potato cakes on each plate, and distribute a generous portion of hot smoked salmon on top of them. Divide the asparagus between the cakes. Place one egg per potato cake on top of the asparagus, and finish it off with a generous dollop of sauce hollandaise. Serve immediately.