Clean the mackerel well, and let them lie a short time in vinegar
and water. Then put them into the fish-kettle with cold water and
a handful of salt. Boil them slowly. If small, they will be
sufficiently cooked in twenty minutes. When the eye starts and the
tail splits they are done. Take them up immediately on finding
them boiled enough. If they stand any time in the water they will
break.
Serve them up with parsley sauce, and garnish the dish with lumps
of minced parsley.
They are eaten with mustard.
For boiling, choose those that have soft roes.
Another way is to put them in cold salt and water, and let them
warm gradually for an hour. Then give them one hard boil, and they
will be done.