Mix together all of the ingredients and allow the sauce to sit at room temperature for a minimum of 1 hour to allow the flavors of the sauce to develop.
GRILLED HANGER STEAK:
Preheat a gas grill to medium heat. If you are using a charcoal grill, build a fire and let it burn down until the coals are glowing red with a moderate coating of white ash. Spread the coals in an even bed. Clean the cooking grate.
Brush the meat with oil and season well with salt and pepper. Grill the steaks over direct heat until marked, about 2 minutes on each side. Move the steaks to the cooler part of the grill and continue to grill over indirect medium heat until the desired doneness is achieved.
Allow to rest briefly before serving, cut across the grain. Serve with the chimichurri sauce.
GRILLED SWEET POTATOES:
Rinse and brush the sweet potatoes and dry thoroughly. Leave the peels on and cut them on a bias into half-inch slices.
In a large bowl, add the olive oil, salt, and pepper. Add the cut sweet potatoes to the bowl and toss them to coat.
Grill the sweet potatoes over direct heat, turning once, until marked on both sides, about 3 minutes per side. Turn the sweet potatoes over and move to indirect heat. Grill the potatoes, covered and turning as necessary, until tender throughout, about 6 to 8 minutes.