PREHEAT oven to 300ºF. Line 15x10x1-inch baking pan with foil; spray with cooking spray. Mix sugar, chili powder and pepper; set aside.
PLACE walnuts in medium bowl. Add oil; toss to coat. Stir in sugar mixture. Spread into prepared pan.
BAKE 20 min., stirring after 10 min. Immediately stir in salt. Cool completely. Store in airtight container at room temperature.