Combine first 4 ingredients in a large bowl. Add chicken; toss to coat. Heat a grill pan over medium-high heat. Coat pan with cooking spray. Add chicken; cook 10 minutes or until done, turning after 5 minutes. Let stand 5 minutes. Thinly slice across the grain.
Bring a large saucepan of water to a boil. Add noodles; cook 2 minutes. Add peas; cook 1 minute or until noodles are tender. Drain. Combine rice vinegar and next 3 ingredients in a bowl. Add noodle mixture; toss to coat. Arrange about 1 cup noodle mixture in each of 4 shallow bowls. Top each serving with about 3 1/2 ounces chicken. Sprinkle with sesame seeds and onions.