Preheat oven to 375 degrees F.
In a small bowl mix together 1/4 tsp of cayenne, paprika, cumin, coriander, garlic, and onion powder. Set aside.
Place salmon fillets skin side down on a small sheet pan. Drizzle with olive oil and sprinkle with a big pinch of salt.
Season salmon liberally with spice mixture and bake for 10 minutes.
In a small bowl, whisk together mayo, yogurt, garlic, lime juice, and remainder of cayenne. Add a pinch of salt and give it a quick stir. Refrigerate until ready to use.
Using 2 forks, shred salmon into large chunks.
Toast tortillas over a medium flame for 10-15 seconds per side, or until lightly charred.