1. Combine butter, chili powder, cayenne, red pepper flakes, and lime zest in small bowl. Brush asparagus with butter mixture, sprinkle with salt, and season with pepper to taste.

2. When grill is medium-hot, scrape grill grate clean with grill brush. Dip wad of paper towels in oil; holding wad with tongs, wipe cooking grate. Grill asparagus, turning once, until just tender and caramelized, 2 to 5 minutes per side (move asparagus as needed to ensure even cooking). Transfer asparagus to platter and serve.

Serves 4 to 6