Pre-heat the oven to 425 degrees C.
Brush a baking dish or skillet with 1 tsp olive oil.
Set salmon filets down into dish — skin-side down if they have skin.
Brush 1 tsp of olive oil over each fillet.
Sprinkle with kosher salt + cracked black pepper.
Season each fillet with 1 tbsp of Cajun seasoning each, patting and massaging the seasoning into the fillet like a rub. Rub onto the sides of the fillets as well.
Place in the oven and bake for 15 minutes or until fillets easily flake. The safe internal temperature for fish is 62.8 °C/145 °F.