For the lemon mousseline:
- In a small casserole with a thick bottom, melt 15 ml (1 tablespoon) of butter at medium heat. Add French shallot and cook, while stirring frequently, for 2 minutes or till it softens. Add white wine. Rise heat at high heat and cook for 1 minute till wine reduces of an half. Add cream and mix. Reduce heat and simmer for about 5 minutes or till preparation reduces of about 125 ml (1/2 cup). Add lemon, salt, pepper and what's left of butter.
- In the blender or mixer, mix the preparation till it's light and foamy. Set aside at warm. (You can prepare the lemon mousse beforehand and set it in a sealed glass container. It can be kept until 4 hours in the refrigerator. Set 30 minutes at room temperature before use. Foam again with a blender or mixer before serving and warm lightly at low heat.)
For the creamy asparagus soup:
- In a casserole melt butter at medium-high heat. Add leek and cook, while stirring from time to time, for 3 minutes or till it soften. Add 1,75 liter (7 cups) of chicken broth, asparagus and parsley. Bring to boil. Reduce heat and simmer for about 6 minutes or till asparagus tenders. Set aside some tops for garnishing.
- With a blender or mixer, reduce asparagus preparation into soft puree, many times if needed. With a fine strainer set over a large bowl, filter the mixture by pressing with a wooden spoon to eliminate all filaments. Set again in a casserole. (You can prepare creamy asparagus soup, until this step, cool down and set in a sealed container. Can be kept till the next day in the refrigerator. Preheat at low heat before carrying on with the recipe.)
- While stirring, slowly add cream and enough chicken broth to obtain desired consistancy. Add lemon zest, salt and pepper, and mix.
- When serving, divide asparagus cream into 8 soup bowls. With a spoon, garnish each portion with lemon mousseline and asparagus tops.