Put the potatoes and leeks in water, and boil until soft. Drain, keeping the water, if you like, as a soup or risotto base.
Mash the vegetables with butter, salt, pepper, grated nutmeg and a little milk. Divide the fillet in two, and place on top of the mash. Cover with a lid, and set over the lowest possible heat to prevent the mash from burning, but enough to let the fish cook in the steam.
Serve in heated shallow bowls, with or without a poached egg.
© 2000 Frances Bissell. All rights reserved.