Position a rack in the upper third of the oven and preheat to 450 degrees F. Whisk 1/4 cup vinegar, 1 tablespoon sugar and the chili powder in a shallow microwave-safe dish. Add the onions, separating them into rings. Cover with plastic wrap and microwave until crisp-tender, 3 to 5 minutes. Toss to coat the onions with the liquid, then let cool.
Meanwhile, whisk 1/3 cup mayonnaise, the cilantro and the remaining 2 tablespoons vinegar and 1 tablespoon sugar in a large bowl. Add the cabbage, jalapenos, 1 teaspoon salt, and pepper to taste and toss. Refrigerate the slaw until ready to serve.
Whisk the remaining 2/3 cup mayonnaise and 1 tablespoon liquid from the pickled onions in a shallow dish. Put the crushed chips in another dish. Coat a baking sheet with cooking spray. Dip the chicken in the mayonnaise mixture and then in the chips; place on the baking sheet. Mist the chicken with cooking spray. Bake until crisp and cooked through, 10 to 12 minutes. Serve with the slaw and onions.
Courtesy of Food Network Magazine