Wash the chervil, dab dry and pluck the leaves from the stems. Put some leaves aside. Whisk remaining leaves, eggs, 1 pinch of salt, milk and mineral water. Stir in flour vigorously, let it swell for about 20 minutes.
Wash the asparagus, peel and cut off the woody ends. Cook in boiling salted water with sugar and 3 tablespoons of lemon juice for 15-18 minutes. Heat oil in portions in a pan and bake about 8 pancakes one after the other, keep warm.
For the sauce, melt butter at medium heat, bring to the boil and skim off the foam with a ladle. Put the egg yolk and white wine in a metal bowl and beat until foamy on a hot water bath.
Add the butter drop by drop while stirring constantly. Season the finished sauce with 1-2 tablespoons of lemon juice, salt and pepper. Arrange asparagus with ham and pancakes on a plate.
Pour some Sauce Hollandaise over the asparagus and garnish with chervil. Add the rest of the sauce.