In a bowl, combine the chopped parsley, chopped cilantro, red wine vinegar, olive oil, minced garlic, dried oregano, crushed red pepper flakes, salt, and pepper. Mix well and let it sit for at least 30 minutes to allow the flavors to meld.
Preheat your grill to medium-high heat. If using charcoal, allow the coals to burn until they are covered with white ash.
Place the chorizo sausages on the grill and cook for about 10-15 minutes, turning occasionally, until they are browned and cooked through.
While the sausages are grilling, slice the rolls or baguettes lengthwise but not all the way through, so they remain hinged.
If desired, spread a thin layer of mayonnaise on the inside of each roll.
Place a grilled chorizo sausage in each roll. If desired, add shredded lettuce and sliced tomatoes.
Spoon a generous amount of chimichurri sauce over the sausage.
Enjoy your meal!