Allow your steaks to sit at room temperature for about 30 minutes prior to cooking. While not required, it allows the meat to cook more evenly.
While the steak is resting, make the chimichurri sauce by placing all the chimichurri ingredients into your food processor or high speed blender and blending well until smooth. Reserve ~1/2 of the chimichurri for sauce to serve on top of the cooked steak, or as dipping sauce.
Pierce the steak with a fork or knife, every ½ inch or so to tenderize the meat.
Marinate the steak in half of the chimichurri sauce for 2-4 hours. If you do not have time to marinate, you can just serve with the chimichurri sauce, however, marinating makes for a more flavourful and tender meat.
Add the oil to a cast iron skillet or pan and heat to high. You want your pan to be hot before adding the steak.
Place the steak in the pan. Do not move the steak until it starts to caramelize.
Cook for approximately 2-3 minutes per side, or until steak reaches your desired temperature. See the notes for cooking temperatures.
Remove the steak from the pan and place it on a plate to rest for ~5 minutes. Place a piece of foil lightly over the top of the steak to retain the heat while it's resting.
Serve the steak by cutting the bavette steak against the grain and topping it with the extra chimichurri sauce. The grain refers to the muscle fibers in the meat. Look for muscle fibers and cut in the opposite direction. Cutting these muscle fibers helps make the meat more tender vs chewy or tough.
Notes
Nutritional values are an estimate and will vary depending on the exact ingredients used.
Let the steak rest for a few minutes after it's cooked to make it even more tender.