Cook edamame according to package instructions; drain. Heat broiler, with rack in top position. In a small bowl, stir together lime zest, honey, and 2 teaspoons soy sauce. Brush a foil-lined rimmed baking sheet with 1/4 teaspoon sesame oil. Add salmon; brush with honey glaze. Broil until salmon is browned and opaque throughout, 6 minutes. Let cool slightly. Meanwhile, in a large bowl, whisk together lime juice, ginger, 4 teaspoons soy sauce, and 1 tablespoon sesame oil. Add cabbages, edamame, and scallions and toss to coat. Flake salmon into salad and toss very gently to combine.