In 12-inch nonstick skillet, heat 1 tablespoon of the oil over medium-high heat. Cook chicken, salt and pepper in oil 8 minutes, stirring occasionally, until chicken is no longer pink in center. Remove with slotted spoon to bowl. In same skillet, heat remaining 1 tablespoon oil over medium heat. Cook onion in oil 3 minutes, stirring occasionally, until tender. Add garlic and cumin; cook and stir 1 minute.