2 bunches frisee torn into bite size pieces (8 ounces each)
Preheat oven to 425 degrees. Line a rimmed baking sheet with aluminum foil and place a rack on top of it. Lay bacon on the rack and top with brown sugar. Top with freshly ground black pepper and bake until sugar is bubbling and bacon is crisp, 10-15 minutes. Transfer bacon to a paper towel lined plate to drain then roughly chop.
In a large bowl whisk together the mustard, vinegar and olive oil. Season with salt and pepper. Add chopped bacon, and frisee and toss well to coat.