Cut tips from both ends of each egg to create a flat surface for the eggs to stand on. Slice each egg in half crosswise. Remove yolks; place in a small bowl and mash. Add green onion, cilantro, pepper, mayonnaise, and mustard; blend well. Spoon about 1 tablespoon of the yolk mixture into each egg half. Top each with cheese; sprinkle with chili powder. Cover and chill or use immediately.