1 lemon, zest and juice
1 onion, thinly sliced
small bunch flatleaf parsley, leaves roughly chopped
8 medium baking potatoes
3 heaped tablespoons plain flour
2 bay leaves
陆 tsp black peppercorns
sea salt and freshly ground black pepper
handful rock salt
1 tbsp vegetable oil
200g/7oz butter
grated cheese, for topping
475ml/17fl oz milk
400g/14oz cod, bones and skin removed
400g/14oz haddock, bones and skin removed
250g/9oz cooked peeled prawns
500g/1lb 2oz boneless, skinless smoked haddock
200g/7oz peas