From GoodFood Fish and Seafood Dishes
1 medium potato, peeled and chopped into small chunks
200ml vegetable stock
large handful of kale, finely shredded
small knob of butter
140g piece skinned smoked haddock
1 heaped tbsp dijon mustard
Boil the potato in the stock for 6 minutes until potato fluffs round the edges and the stock has reduced slightly. Stir in the kale and butter, lower the heat and simmer, covered, for 5 minutes. Lay the haddock on top of the kale and potatoes, cover the pan and steam gently for 5 minutes.
Meanwhile, melt the butter in a microwave or a pan on top of the stove, then whisk in the mustard, a splash of water, a tiny pinch of salt and a good grinding of pepper.
Using a fish slice, lift out the cooked haddock and set aside, keeping it on the fish slice. Mash the potato and kale in the pan with the pan juices. Scoop the mash onto a plate, sit the haddock on top and pour over the sauce.