Bring a small saucepan of salted water to a boil. Add the edamame and cook until tender and bright green, about 3 minutes. Drain and rinse under cold water; set aside.
Cut the top and bottom off each orange, then cut off the peel and white pith. Holding an orange over a small bowl to catch the juice, cut along the membranes to remove the orange segments, letting them fall into the bowl. Squeeze any juice from the membranes into the bowl. Repeat with the other orange.
Whisk the peanut butter, 1/4 cup water, 2 tablespoons of the orange juice, the soy sauce, vinegar, Sriracha and 1/8 teaspoon salt in a small bowl. Toss the lettuce, watercress and half of the chow mein noodles in a large bowl. Divide among plates and drizzle with half the dressing. Top with the chicken, edamame, carrots, orange segments and remaining noodles. Season with salt and pepper and drizzle with the remaining dressing.