In a small bowl whisk together chili powder, cumin, paprika and onion powder. Brush both sides of salmon with olive oil. Season with salt and pepper, then sprinkle spice mixture evenly over each fillet.
Preheat grill to medium-high heat. Grill salmon on a piece of foil, skin side down (skin will stick to foil, you can easily remove fish with spatula and skin will stick to foil) and grill about 10 minutes, or to desired doneness. Remove from grill and squeeze fresh lime juice over tops.
Divide all salad ingredients (except cilantro) among 4 plates then top with salmon fillets. Drizzle with dressing (see Note below), garnish with fresh cilantro leaves and enjoy.
DRESSING: Add all dressing ingredients except for milk and oil to a food processor, pulse until well blended. Add milk and olive oil, 1 tablespoon at a time, to reach desired thickness. Store in refrigerator in an airtight container.