Combine paprika, onion and garlic powder, salt, oregano, thyme, black pepper, cayenne pepper and brown sugar in a small bowl.
Cut salmon into 4 portions and brush with oil. Distribute the rub over the salmon generously coating all surfaces. Place salmon on a shallow baking pan with sides.
Bake for 15 to 20 minutes, until fish flakes easily.
Coarsely chop grapefruit into bite size pieces. Combine all salsa ingredients and serve with salmon. Grapefruit salsa can be made ahead and refrigerated until ready to serve.
