Heat oil in a large nonstick skillet over medium-high heat. Brush fish with soy sauce. Combine 2 teaspoons pepper and sesame seeds; sprinkle evenly over fish. Add fish to pan, and cook 2 minutes on each side or until fish flakes easily when tested with a fork or until desired degree of doneness.
Combine 2 tablespoons water and next 5 ingredients (through ginger) in a small bowl. Combine slaw and onions in a large bowl. Drizzle vinegar mixture over slaw mixture; toss to coat. Serve with fish.