Quarter the potatoes and bring to boil in a large pan of water. Cook for 15 minutes or until soft, then drain, mash with the butter and season with salt

Meanwhile fry off the onion in the oil until softened. Add the milks, bay leaf & peppercorns and let simmer for a minute

Add in the cod fillets, cover and poach gently for 10 minutes until the fish is cooked

Remove the fish and keep warm. Add the mustard to the milk mixture, bring to the boil then simmer for 5 minutes

Divide the mash between the plates and lay the cod fillets on top

Remove the bay leaf then spoon the mustard sauce over the fish

Serve with seasonal vegetables