In a small bowl, mix together chilli powder, garlic granules, onion powder, sugar, salt, allspice, cumin, white pepper and paprika. Reserve 1 1/2 tablespoons of the mixture for the vinaigrette, and sprinkle remaining spice mixture over salmon fillets. Cover, and refrigerate for 6 hours.
Preheat barbecue for high heat.
Lightly oil barbecue grate, and spread a small amount of olive oil on salmon fillets. Cook salmon 4 to 5 minutes per side, or until easily flaked with a fork.
In a small bowl, mix together tomato juice, vinegar, tomatoes, olive oil and reserved spice mixture to make vinaigrette. Place salad greens in a large bowl, drizzle with vinaigrette, and toss to coat.
Divide greens among individual serving plates. Top each plate with a salmon fillet, and spoon any remaining vinaigrette over the salmon.
Onion powder is available in Asian shops and some larger supermarkets. In a pinch, use finely minced onion or shallot to taste, or omit altogether.