brussel sprouts with mustard

http://www.slate.com/id/2287749 

Caramelized Brussels Sprouts with Mustard
Trim a pound of sprouts, then halve or quarter lengthwise. (The flat-cut surfaces brown better.)
Dice a medium onion. Cook the onion in enough extra-virgin olive oil to cover the bottom of a heavy 10- to 12-inch skillet and a good pinch of sea salt for a few minutes.
Reduce the heat to medium low and add the sprouts.
Cook uncovered, turning occasionally, for about 45 minutes, until the sprouts have browned nicely.
Add about a half cup of whole grain mustard, stir, and cook for another 10 minutes.
Serve immediately.
From Jim Dixon.