Step 1

Heat the oil in a large saucepan, tip in the leeks and fry gently for 5 mins until softened, but not coloured. Add the potatoes and cook for a further min. Pour in stock and lemon zest, cover and simmer for 12-15 mins or until the potatoes are tender. With a slotted spoon, remove half the potatoes and leeks from the stock and set aside.

Step 2

Transfer the remaining potatoes, leeks, stock and milk into a blender or food processor and whizz until smooth. Pour back into the pan, add the sweetcorn, fish and reserved vegetables. Cover and gently heat for 3-4 mins until the fish is just cooked through – don’t boil. Stir in chives and cream, if using, then season to taste.