For the white wine sauce:
- In a medium casserole, melt butter at medium heat. Add flour and mix. Cook, while stirring, for 1 minute. Add white wine and mix well with a whisk. Add milk and cream. Whisk non-stop and cotinue cooking for about 5 minutes or until the sauce thicker.
- Remove casserole from heat. Add Gruyere cheese, lemon juice and nutmeg. Salt and pepper (do not salt too much, since salmon already contains lots of salt). Stir with a wooden spoon until cheese melt and the sauce homogenize. Set aside at warm.
- *You can prepare the sauce beforehand, cool down and cover. Can be kept till the next day in the refrigerator. Warm up carefully with a bain-maire before making the crepes.
For the garnishing:
Cut the hard part of asparagus for about 5 cm (2 inches) from the base (curve lightly the stem and it will break right away where its harder), peel with a peeler starting from the top to the base. Wash asparagus and drain with a paper towel.Set asparagus in a steamer set in a casserole with boiling salted water (asparagus shouldn't be in touch with ater). Cover and cook for 3 or 4 minutes or until asparagus tenders, but still crispy. Rince under cold water. Drain and set aside. *You can prepare asparagus beforehand, let it cool down and set in a sealed container. Can be kept till the next day in the refrigerator.