Begin by making the chimichurri sauce. In a medium bowl, combine the chopped parsley, minced garlic, oregano, red wine vinegar, olive oil, red pepper flakes, salt, and black pepper.

Stir the chimichurri sauce well and let it sit at room temperature for at least 15 minutes to allow the flavors to meld together.

Preheat your outdoor grill or an indoor cast-iron grill pan to medium-high heat.

Using a sharp knife, butterfly the sausages by slicing them lengthwise down the middle, being careful not to cut completely through so they open like a book.

Place the butterflied sausages flat-side down on the hot grill. Cook for 5 to 7 minutes until the inside is nicely browned and slightly charred.

Flip the sausages and cook for an additional 5 minutes on the skin side until they are fully cooked through and the juices run clear.

While the sausages are finishing, slice your bread rolls open and place them cut-side down on the grill for 1 to 2 minutes until lightly toasted and warm.

To assemble the choripán, place a hot grilled sausage into each toasted roll and spoon a generous amount of the chimichurri sauce over the meat. Serve immediately with extra sauce on the side for dipping.