Make the Chimichurri. Whisk together all of the ingredients in a bowl. Adjust for salt and other seasonings to preference. Refrigerate in a sealed container until ready to use. It is best to make it 1 day ahead to let the flavors develop.
Make the Chicken. Add the chicken to a large bowl or sealable baggie and cover with half of the chimichurri. Be sure to rub the chicken good with the marinade. Marinate for 15-20 minutes.
Heat a grill or a large pan on the stovetop to medium heat. Lightly oil the grates or pan.
Add the chicken and grill or pan cook 5-6 minutes per side, or until cooked through. Chicken should measure 165 degrees F (74 C) internally when measured with a meat thermometer.
Toss with the remaining chimichurri, or serve the chimichurri on the side.
Squeeze with lemon and enjoy.
