Inspired by Argentinian choripán, this sandwich stars boldly spiced chorizo and chimichurri, Argentina’s signature sauce. Tangy with vinegar and grassy with cilantro (or parsley, or both) chimichurri balances the richness and fattiness of sausage. It’s essential to use fresh Mexican-style chorizo, which is raw and made with ground pork, as opposed to the Spanish dry-cured or smoked variety; make sure it is link-style chorizo in natural casing. To help the sandwiches remain intact when eaten, we cut a baguette into four sections, then slice through lengthwise on just one side, creating a hinged shape reminiscent of a hot dog bun.