Step 1
Preheat the oven to 425 degrees, In a small bowl, mix together the brown sugar, kosher salt, ancho chili powder, regular chili powder, garlic powder, onion powder, and black pepper.
Step 2
Brush the salmon with olive oil. Sprinkle with the spice mixture and rub to cover the salmon with the spice rub. Place the salmon on a baking sheet covered with foil. Bake for 8-10 minutes for thinner fillets, 12-16 minutes for medium thick fillets, and 18-22 minutes for thick fillets. Salmon is ready when it reaches about 145 degrees.
Step 3
To make tostadas: Place the tortillas on a baking sheet or directly on the oven rack. Cook for about 4 minutes on each side until they are crispy. You can cook these at the same time as the salmon or make them while you prep the salmon.