PLACE chicken breasts on a cutting board. Cover with a large piece of wax paper. Using a rolling pin or mallet, pound thickest part until chicken has an even thickness. Transfer to a pie plate.
WHISK rice vinegar with soy sauce, sesame oil, sriracha, sugar and salt in a small bowl. Pour 1⁄4 cup sauce over chicken, coating evenly. Reserve remaining sauce for noodles.
HEAT a medium non-stick pan over medium. Add chicken and cook until springy when pressed, 6 to 8 min per side. Transfer to a cutting board. Let stand for 5 min, then slice into bite-sized pieces.
COOK ramen noodles, following package directions but omitting seasoning packet, until tender, 3 to 4 min. Drain and rinse under cold running water. Drain well and return to pot. Stir in reserved sauce, edamame, pea sprouts, green onions and chicken.