Wash and trim asparagus.

Juice lemon. Put the juice in a small heavy saucepan, bring to a boil, and reduce by half.

Once it is reduced, add butter, a little at a time, stirring well after each addition, so that it melds into a creamy sauce. The amount you need will vary by the size of your lemon and how tangy you like the sauce. Keep sauce warm over low heat.

Steam asparagus 5-10 minutes, until tender and done to your taste. Timing will vary by the size and freshness of the spears, as well as your taste.

Either pour sauce over the spears when you plate them, or pass it on the side.