Cook rice according to package directions, omitting salt and fat. Keep warm.
Toss chicken with cornstarch and fish sauce. Heat 1 tablespoon oil in a large nonstick skillet over medium-high heat. Add chicken to pan; sauté 5 minutes. Remove chicken from pan. Heat remaining 1 teaspoon oil in pan. Add onion, garlic, and ginger to pan; sauté 1 minute. Return chicken to pan; cook 1 minute or until done. Stir in coconut milk, Sriracha, sugar, and juice; cook 45 seconds or until thoroughly heated. Sprinkle each serving with 1 1/2 teaspoons cilantro. Serve chicken mixture over rice with lime wedges.