I just know I am going to regret asking,
but where is "Martinez & Feldmans" and "Paco Goldbergs"
there I did it, I regret it but I did it any way!
Brisket is called Pecho de Res...If there's a Supermercado Nacional nearby, they seem to use decent butchers for their domestic beef. They also have pretty good imported beef, but I doubt they'd have brisket.
Talk to the german butcher in Sosua, tell the wife you want it to cook with potatoes and cabbage.