White Asparagus with Potatoes and Chervil Sauce

For the asparagus: Rinse the asparagus, peel, snap off the woody ends and cook in boiling salted water with the butter and lemon juice for about 18-20 minutes.

For the potatoes: Scrub the potatoes thoroughly under running water then cook in salted water for about 25 minutes, until fork-tender.

For the chervil sauce: Melt the butter in a saucepan, stir in the flour and cook until light golden brown and nutty. Gradually whisk in the milk, bring to a boil then reduce the heat and simmer for about 10 minutes, stirring occasionally. Add the lemon zest and season with salt, pepper and nutmeg. Mix in 1/2 cup asparagus cooking liquid.

Just before serving, stir the chervil into the sauce.