Marinate Steak: Combine Flank Steak Marinade ingredients in a small bowl; whisk to combine. Pat flank steak dry with a clean paper towel. Season with salt and pepper - press into the meat. Place steak in a reusable silicone bag or glass container. Pour marinade over top and ensure the steak is fully coated.  Let marinate at least 30 minutes. 

Cook Steak: Bring a large cast iron skillet to medium-high heat. Add oil, swirl to coat the pan. Remove flank steak from the marinade letting excess liquid drip off; discard marinade. Place steak in the hot pan and sear 4-5 minutes per side and then 1-2 minutes per side until the internal temperature towards the thickest part of the steak reaches 130-135 degrees F. for a medium-rare finish (use an internal meat thermometer for accuracy) - during the cooking process turn down the heat, as-needed, if your skillet really gets hot and/or add a little extra oil if the pan is dry - to avoid burning. 

Rest + Serve: Remove from skillet and place on a cutting board to rest 10 minutes. Slice against the grain and serve - we love serving it with this Homemade Chimichurri Sauce or in these Steak Fajita Bowls.