Combine onion, lime juice, soy sauce, and sesame oil; stir with a whisk. Crush noodles from ramen noodle soup package (discard seasoning). Add 1/3 cup crushed noodles, cooked edamame, and avocado to soy sauce mixture; toss gently. Divide chopped romaine lettuce among 4 plates; top with avocado mixture. Top with sections from clementine.