Combine first 6 ingredients, and sprinkle over all surfaces of the fish. Grill fish, skin side up, on lightly oiled grates over medium-high heat (350° to 400°) for 4 minutes. Turn fish over, and grill 4 minutes or until fish becomes opaque and begins to flake. Remove skin, and break fish into chunks.
Lightly coat tortillas with cooking spray, and grill 1 to 2 minutes each side.
Fill each tortilla with fish and top with Nectarine-Avocado Salsa and Zesty Sour Cream. Serve immediately.