Wash lemon hot, grate dry, cut fruit into slices. Wash white asparagus, peel, cut off woody ends. Wash green asparagus, peel lower third and cut off woody ends
Boil 3 litres of salted water. Season with sugar and lemon slices. Let the asparagus peel in it for about 20 minutes at medium heat. Then pour through a sieve
Peel, wash and halve the potatoes and cook in boiling salted water for about 20 minutes. Bring the asparagus stock to the boil and cook the white asparagus for about 15 minutes. After about 10 minutes add the green asparagus. Wash the parsley, shake dry, pluck the leaves from the stems and chop finely
Melt the butter. Beat egg yolks, white wine and vinegar over a hot water bath until frothy. Add butter, except for 1 tbsp for the potatoes, drop by drop while stirring. Season to taste with salt and pepper.
Drain the potatoes and toss in the remaining butter and parsley. Arrange asparagus, sauce, potatoes and ham