Preheat the oven to 180 degrees Celsius.
Peel the potatoes and cut into 3mm slices. Do not wash them, this will preserve the maximum amount of starch.
Butter 6 individual tart tins with the melted butter. Layer the slices of potatoes in the tins in a rosette shape, lightly salting them as you go. Place in the oven and cook until the bottoms are golden brown and the potatoes are soft all the way through.
Use a sharp knife to split the vanilla pod in half and scrape out the seeds. Place the vanilla pod and seeds in a pan, add olive oil and heat for about 3 minutes until the pod is warm. Remove from the pan and cut into 5cm lengths and insert 2 pieces into each cod fillet. Keep the vanilla infused oil aside to use as a drizzle.
Heat a non-stick frying pan and then place the cod fillets in the pan skin side down. Cook for 3 minutes on each side then lower the heat and cook for a further two minutes.
Season the cod fillets with salt and pepper.
To serve: turn the potatoes out of the tins onto individual dinner plates. Place the cod fillets on top of the potatoes and garnish with fresh herbs or salad. Drizzle the vanilla scented olive oil over your fish and serve immediately.
«For a lighter dish, serve the cod fillets with some salad or citrus fruit»