The potatoes were boiled in salted water for twenty minutes, and the sprouts for seven.
The fish was added to a skillet already heated, and with a knob of butter sliding around. Then about 100mls of milk was added. The fish should be cooked at a slow simmer under glass, for between 12 and 15 minutes (the fish changes colour when it is nearly ready). It does not need to be turned.
Decant the vegetables to the serving plate, add the fish (carefully!), and drizzle some of the poaching milk over it.
This fish poaches very well, though it is not usually included in lists of fish which do. Delicious flavour, and delicate texture. One of the most popular dishes on this site, as of March 2021.