In a small bowl, whisk together soy sauce, vinegar, sugar, 1 1/2 tablespoons olive oil, sesame oil, and salt and pepper to taste.
In a bowl, toss the cabbage, carrot, and scallion with 2 tablespoons of the soy sauce mixture.
Remove tough muscles from side of each scallop if necessary.
Pat scallops dry with paper towels and season with salt and pepper.
In a heavy non-stick skillet just large enough to hold scallops in one layer, heat remaining 1/2 tablespoon olive oil over moderately high heat until hot but not smoking and sauté scallops until golden and cooked through, about 2 minutes on each side.
Transfer scallops to a bowl and add remaining soy sauce mixture to skillet and boil until reduced to a glaze.
Add glaze to scallops and toss to coat well.
Remove scallops and keep warm then add the slaw to the skillet and cook over moderately high heat, stirring, just until cabbage is wilted, 1 to 2 minutes.
Season slaw with salt and pepper.
Serve slaw topped with scallops and garnished with scallion greens.