In 12-inch nonstick skillet or wok, heat 1 tablespoon of the oil over medium-high heat. Swirl pan to coat sides with oil. Add chicken; cook 6 to 8 minutes, turning once, until cooked through. Add serrano chile, garlic and gingerroot; cook 30 to 60 seconds, stirring frequently, until fragrant. Transfer to bowl; cover and keep warm.