My butcher usually keeps two special cuts aside when he gets a new carcass — the poire and the merlan — and I have the right of first refusal. I hardy ever refuse.
These are very fine cuts, one is oblong and looks like a fish (merlan being a whiting) and the poire looks like a big pear. They come from near the topside, in English butchery terms. For French butchers, they are near the tranche. It is lean and delicate meat and not so well known because there is just about a pound of it on an entire cow.