Modified from Jamie O. The short version: Steam the asparagus (3-4 minutes). Shake together in a jar: 1 T mustard, 3 T evoo, 1 T white wine vinegar, 1 T white wine, a little salt, a little pepper, some chervil. Pour vinaigrette over asparagus.
Jamie's vinaigrette was a titch vinegary for me, so I dumped my jar into a pan and reduced it all a little bit. The yumminess remained without the overpowering acidity. Delish!