1. Heat a large nonstick skillet over medium-high heat. Add oil to pan; swirl to coat. Add chicken; cook 4 minutes on each side or until golden. Transfer chicken to a 4-quart electric slow cooker coated with cooking spray.
2. Combine soy sauce and next 5 ingredients (through garlic); pour over chicken. Cover and cook on LOW for 2 1/2 hours or until chicken is tender. Transfer chicken to a platter; keep warm.
3. Pour cooking liquid through a sieve into a small saucepan to measure 1 1/4 cups. Discard solids. Bring cooking liquid to a boil over medium-high heat. Combine cornstarch and 1 tablespoon cold water in a small bowl. Add cornstarch mixture to sauce, stirring with a whisk until blended. Return to a boil. Cook 1 minute or until sauce thickens, stirring constantly. Serve sauce over chicken. Sprinkle with sesame seeds and green onions.