Place pecans on a baking sheet and bake until golden brown and fragrant, about 10 minutes. Set aside.
Heat a small skillet over medium high heat. Add pancetta and cook until golden brown. With a slotted spoon transfer pancetta to a plate lined with paper towels.
In a small bowl add the sugar, vinegar, dry mustard, kosher salt, oil, grated onions, lemon zest and poppy seeds. Stir to combine.
In a large bowl, combine the kale, cabbage, brussel sprouts, carrot and cranberries. Add the lemon juice to the salad and toss to combine. Add pecans, pancetta and feta cheese. Dress the salad with enough salad dressing to evenly coat the greens, but don't overdo it. If there's leftover dressing, save it for another salad. Serve.