In a food processor, combine the cilantro, parsley, oregano, shallot, garlic, and jalapeño.
Add the lemon juice, red wine vinegar, olive oil, salt, and pepper and pulse until well combined and finely chopped.
Place the chicken in a baking dish, season with salt and pepper, and cover with a ¼ cup of the chimichurri. Turn to coat the chicken completely. Marinate for 20 minutes to 2 hours in the refrigerator.
Take the chicken out of the fridge to warm up slightly while heating the grill to medium high. Cook the chicken about 5-6 minutes per side, until juices run clear.
Serve with extra chimichurri on the side.
*Chicken breasts, drumsticks, or bone-in thighs may be used instead. If using chicken breasts, cut them in half if they are large, and pound to ½ inch thick, if necessary. They will cook more quickly than thighs, around 4 minutes per side. Bone-in cuts will cook more slowly, so give them a couple of extra minutes.*Although chimichurri sauce will keep for up to 2 weeks in the refrigerator, it tastes best when used within 1-2 days.