Wash and peel asparagus, discard the bottom hard part of the stem. Cut them into 1" pieces and cover with water, add salt, lemon slices, and sugar. Cook for 10-15 minutes until tender.

Drain, reserving two cups of the water it cooked in.

Melt butter or margarine, add flour, stir in milk, cook over medium heat, stirring until thickened.

Add the two cups of reserved water and the asparagus pieces, bring to boil and then remove from heat.

Beat the egg yolk with whipping cream and stir into soup.

Season with salt and pepper.