Wash and peel the asparagus and cut off the woody ends. Cook the asparagus in boiling, lightly salted water, covered with sugar for 15-20 minutes
Peel and finely chop the onion. Wash the basil and chop finely, except for a little to garnish. Puree briefly with 2-3 tbsp. of the asparagus water
Lift out the asparagus and keep warm, measure 3/8 l asparagus stock. Steam onion in hot fat until translucent. Dust with flour and sauté briefly. Stir in asparagus stock and milk. Bring to the boil and simmer for about 5 minutes. Season to taste with salt and pepper
Pull the sauce off the stove. Whisk egg yolk and 3 tbsp. sauce. Stir back into the rest of the sauce (do not boil any more!). Stir in basil. Arrange asparagus with sauce, salmon and cooked ham. Garnish with the rest of the basil. To this taste roasted new potatoes
Instead of the classic butter sauce, here you get a slimmer modified béchamel. Basil provides additional vitamins. Also delicious: chervil or tarragon