Have ready a large bowl filled with ice water. Bring a pot of water to a boil, add salt and cook noodles until tender. Drain and rinse in cold water, rubbing to remove surface starch. Place immediately in bowl with ice water until cold. Drain well. Meanwhile, cook edamame according to package directions. Cool. Mince white part of scallions. Cut green stems in 1 1/2” lengths, and slice again lengthwise to make thin strips. Grate lime peel, then cut limes in half and juice. Combine lime juice, grated peel and soy sauce.
To serve, place noodles in serving bowl. Add beans and scallions. Add soy sauce and lime mixture, and combine gently but thoroughly. Serve cold.