I recently went to Colombia for some exciting r&r. One place I hit was Pereira. I swear by all things that are holy that the chorizo in that town, and surrounding "burbs" such as Santa Clara have the best chorizo this side of the Atlantic. The casing is filled with cuts rather than a mash and is wonderfully seasoned with herbs and spices other than paprika. Does anyone know of a place in the five boroughs where that specific chorizo is sold?
This may be a year too late, but I just bought colombian chorizo yesterday at "Boina Roja" butcher in jackson heights -- next to the Boina Roja steakhouse on 37th Ave betw. 80th and 81st streets; not sure if its the same as in Pereira, but it's pretty darn good. And the butcher will explain how to cook it.
The Local Trade Fair here in Jackson Heights on 37th ave, has quite a bunch of different chorizo's and so does the local Met supermarket. Also given that Jackson Heights has a pretty strong Colombian population you can probably just poke around and ask, and someone would tip you off to a butcher that makes it.