Set oven or air-fryer to 400f (204C).
Add the fillets to a mixing bowl, along with the seasoning. Gently massage the seasonings and oil into the fish. Let the fish marinate for 10 minutes covered at room temperature, or up to 8 hours in the fridge.
For the oven:
Line a baking sheet with parchment paper, then spread out the fillets. Place any capers that have fallen off on top of the cod. Bake in the oven for 12 – 15 minutes, or until the fish is lightly golden and cooked through.
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For the air-fryer:
Depending on the size of the air fryer, you may have to cook the fish in batches. Spray the inside of the air fryer basket, then spread out the fillets. Place any capers that have fallen off on top of the cod. Bake in the oven for 8 – 10 minutes, or until the fish is lightly golden and cooked through.
Allow the fish to cool before storing.
An airtight container will keep this in the fridge for 3 – 4 days. If you wish to freeze it, I recommend separating the fillets and placing them in individual freezer-safe sandwich bags. They will last for 2 – 3 months in the freezer.