Peel asparagus well, remove woody parts and simmer slowly in lightly salted water for 15-25 minutes depending on thickness. Quench in ice water and pat well. Season with salt and freshly ground white pepper. Coat in flour, briefly beaten egg and breadcrumbs. Fry in hot fat until golden, drain on paper towels and serve with the sauce. For the cream tartare sauce, finely chop the ingredients. Rinse chopped onions in hot water, rinse in cold water and squeeze well. Quickly mix all the ingredients listed and season well (stirring too long will make the sour cream thin!).