Heat grill to high and oil grates. Sprinkle salmon with salt and pepper; set aside.
In small saucepan, combine rice vinegar, ginger, honey and olive oil, and bring to simmer over high heat. Stir in grapes and scallions, and season with salt and pepper. Set aside off heat.
Grill salmon, skin side up, 5-6 minutes. Turn and grill another 2-3 minutes, or until salmon reaches desired doneness.
Divide rice among four bowls and top with cabbage and salmon. Spoon grape mixture over top and sprinkle with sesame seeds. Serve with soy sauce, if desired.
Nutritional information per serving: 487 calories; 23 g protein; 69 g carbohydrates; 13 g fat (24% calories from fat); 3 g saturated fat (6% calories from saturated fat); 43 mg cholesterol; 301 mg sodium; 6 g fiber.