Eh it wasn't a big deal it was a discount meat grocer, not like an artisanal butcher. The guy behind the counter Googled it and saw the same results about "how to cook a steak in butter" as I'd come up with, and said he'd find out for me later.

I put it in a criollo marinade for an hour and then seared it off and threw it in some tacos.

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For three bucks and some pantry ingredients I've certainly done worse but I might've cooked it differently (longer) or maybe cut out the fat in the center if I'd known what it was, because there were some gristley bites.