So, to make this recipe, you fry up a few strips of bacon, cut into small pieces (I'm sure pancetta and the like work well here, too). Then you add some onions or shallots, and let those soften, then deglaze the pan with a bit of red wine vinegar and mustard. This sauce makes the dressing for the salad. Place the greens in a warm bowl, toss with the bacon dressing, and then top each portion with a poached egg.
I thought this salad would make a great main course, and that's how I served it. Unfortunately, a series of circumstances made it a really just-okay salad. First of all, I'd never eaten raw mustard greens before; their name is no joke. It was like eating greens laced with wasabi. Some bites were mild enough, while others brought on hot tears. I could barely taste the bacon! Eating it, I thought that perhaps quickly blanching the greens might make them a bit milder, one possible tweak to make this recipe a bit more bearable.
Sidebar: Jacques Pepin makes a similar salad, with frisee instead of greens and the bacon on top instead of incorporated into the dressing. Looks really good. You can watch the episode of Pepin's show where he makes the salad here.