How to Make It
Heat 1 1/2 teaspoons oil in a large skillet over medium-high heat. Sprinkle chicken with 1 teaspoon chili powder. Add chicken to pan; cook 4 minutes on each side or until done. Remove chicken from pan; let stand 5 minutes. shred chicken into large pieces with 2 forks.
While chicken cooks, heat 1 1/2 teaspoons oil in a medium saucepan over medium heat. Add 1/2 cup onion; sauté 5 minutes. Add remaining 2 teaspoons chili powder, tomato sauce, 1 tablespoon vinegar, 1 tablespoon sugar, 1/2 teaspoon salt, and 1/4 teaspoon pepper to pan; bring to a boil. Reduce heat, and simmer 5 minutes. stir in chicken; keep warm.
Combine remaining 1 tablespoon oil, remaining 1/4 cup onion, remaining 2 tablespoons vinegar, remaining 1 1/2 teaspoons sugar, remaining 1/4 teaspoon salt, remaining 1/4 teaspoon pepper, and coleslaw. top bottom halves of buns evenly with chicken mixture, slaw, and top halves of buns, or serve slaw on the side.