The finished recipe. Haddock in Parsley Sauce with Mash and PeasIngredients 1 to 6. 180 g Haddock fillet (Weighed raw, skin on unless the method says otherwise. Cooked weight is roughly 20% less for the same fillet.). 200 ml Skimmed milk. 10 g Plain flour. 6 g Butter. 180 g Potato (Raw, peeled weight.). 80 g Frozen peasIngredients 7 to 8. A large handful, chopped Fresh parsley. Plenty Black pepperStep 1. Boil the potato in chunks for fifteen minutes, drain, and mash with a splash of the milk and a good pinch of salt.Step 2. Put the haddock in a small pan with the rest of the milk, bring it to a bare simmer and poach for six minutes. Lift the fish onto a plate and keep the milk.Step 3. Melt the butter in the same pan, stir in the flour for a minute, then add the warm poaching milk a little at a time, whisking, until smooth. Simmer for three minutes.Step 4. Stir in the parsley and pepper, boil the peas for three minutes, and pour the sauce over the fish next to the mash.