Heat the oil in a saucepan, add the shallots and garlic and cook for 3–4 minutes until softened. Add the potato, milk and measurement water and season to taste. Bring to the boil, then reduce the heat and simmer for 5–6 minutes.
Stir in the kale and cook for a further 10–12 minutes until the vegetables are tender. Stir in the haddock and simmer for 2 minutes or until cooked through.