In an appropriately sized large pan, slowly fry your onion and leek with around 5 tablespoons of coconut oil for 5 minutes until soft and tender. Remove and discard the fluffy tasteless core from the courgettes and grate the rest into the pan.
Chop the potatoes into rough 2cm dice and add to the pan. Give everything a good stir and then add the anchovies. Allow to cook down by half before adding your milk and stock.
Bring to the boil and simmer for half an hour until the potatoes are tender. At this point, add your cod and simmer for a further 15 minutes until the flesh flakes away; feel free to stir and break up the fish, but it's quite nice to leave some big chunks as well.
Season carefully to taste. Divide between your bowls, and serve with a small handful of parsley, spring onion and lemon juice.
Sprinkle a little orange zest over the parsley and spring onion. It really works with the cod.