• Start by choosing a great flank steak at the store. Look for one that is uniform in thickness if you can find it, to ensure even cooking. (Costco sells fabulous flank steaks in a 2 pack. Cook one and freeze the other for next time!)
• Unroll the steak and season generously with salt and pepper on both sides.
• Place the steak in a large ziplock bag, or in a glass casserole dish with a lid.
• Rub about 1/4 cup homemade Chimichurri sauce (click here for the recipe) all over both sides of the flank steak. OR you can use your favorite marinade (see notes for a different marinade idea).
• Seal the bag or put the lid on your dish. Marinate in the fridge for at least 2 hours, or up to 24 hours. Turn the steak at least once or twice during the marinade (which is why I prefer using ziplocks; I don't like getting my hands messy)
• Take the steak out of the fridge and let it sit on the counter for about 30-40 minutes before cooking, so that it starts cooking at room temperature.

How to grill flank steak

• Make sure your grill has been scraped clean of any remaining bits from the last time you grilled.
• Heat your grill to the highest setting, about 450 degrees. Let the grill heat for at least 15 minutes to make sure it's REALLY hot.
• Discard any marinade that is not sticking to your flank steak.
• Just before you are ready to put the steak on the grill, oil the grates. I like to add a little olive oil to a bowl, dip a paper towel in it lightly (don't soak it) and rub the grill grates where the steak is going to go.
• Place your steak on the grill and shut the lid. Set a timer for 1 minute, or 2 minutes if it's a very thick steak.
• Open the lid and flip the steak. Shut the lid and set a timer for another 1-2 minutes.
• After this initial sear, don't open the lid again. Simply turn the heat down to medium.
• Cook the steak over medium heat for 6-10 minutes, opening the grill to flip the steak one time at the halfway point. Keep an eye on it and don't walk away. Use your meat thermometer. Rely on the meat thermometer, not on cooking times. See notes below for doneness temperatures.
• When your steak has reached the temperature that is 5 degrees BELOW what you want your final temperature to be (see notes), remove from the grill and place on a rimmed platter to catch any drippings.
• Tent your steak with foil to keep it warm while it rests for 5 minutes. You need to let the steak rest, or all the juices will run out of the steak when you slice it.
• Transfer the meat to a cutting board. Use a sharp knife to slice the steak into thin 1/4 inch strips, on the bias against the grain. "On a bias" means you should be cutting at a 45 degree angle, not straight up and down like you would slice bread. (This increases the surface area of each bite, and shortens the muscle fibers, enhancing tenderness.) "Against the grain" means that your knife should be cutting the meat perpendicular to the lines of muscle ("grain") that you can see on the flank steak. See photo.
• Serve the flank steak with extra Chimichurri Sauce!

How to oven broil flank steak

• Turn your broiler on to high heat. Let it heat up for 15 minutes at least, to make sure it's good and hot.
• Meanwhile, place your room temperature flank steak on a greased broiling pan, or on an oven-safe cooling rack that has been set on a baking sheet. (Line the baking sheet with foil for easy clean up. See photo)
• Position your oven rack so that the meat will be about 3-4 inches from the heat source.
• Broil the flank steak for about 11-14 minutes (for Medium Rare. See how to measure doneness temperature in the notes below.) At the halfway point (after about 6-7 minutes), remove the pan from the oven, shut the oven door, and flip the steak with tongs. Put the pan back in the oven. (you always want to keep the oven door shut as much as possible so that your oven doesn't cool down.)
• When the steak reaches the temperature that is 5 degrees BELOW what you want your final temperature to be, remove it from the oven.
• Place the steak on a rimmed platter to catch any drippings.
• Tent your steak with foil to keep it warm while it rests for 5 minutes. You need to let the steak rest, or all the juices will run out of the steak when you slice it.
• Transfer the meat to a cutting board. Use a sharp knife to slice the steak into thin 1/4 inch strips, on the bias against the grain. "On a bias" means you should be cutting at a 45 degree angle, not straight up and down like you would slice bread. (This increases the surface area of each bite, and shortens the muscle fibers, enhancing tenderness.) "Against the grain" means that your knife should be cutting the meat perpendicular to the lines of muscle ("grain") that you can see on the flank steak. See photo.
• Serve the flank steak with extra Chimichurri Sauce!