Parsleyed Cod with Roast Potatoes and Mustard Butter Sauce

I have changed this classic cod and parsley combination to give a purée of parsley mixed with spinach, which is spread over the fish, so that the parsley flavour comes through in every bite. This dish is a complete meal: the roast potatoes and sea kale finish it off perfectly.

The pig’s caul is only available by order from your butcher. It works like a net to hold the parsley purée in place. If it’s unavailable, wrap the cod in buttered foil and steam it instead of pan-frying and ro