Spray a large nonstick skillet with cooking spray and set over medium heat. Add the Canadian bacon and cook until crisp, stirring often, about 4 minutes. Transfer to the bowl with the frisée.
Place the skillet back over medium heat and swirl in the olive oil. Add the shallots; cook, stirring often, until softened, about 2 minutes. Stir in the mustard and Worcestershire sauce; scrape up any browned bits in the skillet for a few seconds. Pour in the vinegar; bring to a full simmer.
Pour this shallot-laced dressing over the frisée and Canadian bacon, scraping everything out of the skillet and into the bowl. Toss well and divide among 4 plates.
Fill a large high-sided skillet or sauteuse pan halfway with water; bring to a boil over high heat. Reduce the heat to low so the water barely simmers. Crack an egg into a small ramekin or custard cup, then slip the egg into the water. Repeat that with the other 3 eggs in separate spots in the water. Cook for 5 minutes undisturbed. Pick up 1 poached egg at a time with a slotted spoon, draining off any excess water and set it on top of a salad. Sprinkle the salads with cracked black pepper to taste.