Authentic Swansea Baked Mackerel

Clean whole fresh mackerel. Rub the inside with a mixture of softened butter, grainy mustard, and lemon juice.

Press the fish into a plate of coarse oats until well-coated. Place in a baking dish and dot with extra butter.

Bake at 200°C (400°F) for 15–20 minutes until the oats are crispy and the fish is flakey. A traditional coastal dish from the Swansea area.