• Add all of the ingredients to a blender (I use my Magic Bullet because it has a small carafe and we aren’t making a huge amount of marinade).
  
• Blend the marinade until everything is well-combined. After the marinates sits for a while, there will be some separation - simply blend it again or stir it well before using.
  
• Use the marinade or save it in an airtight container in the refrigerator for up to 1 week. To marinate flank steak or skirt steak, place the meat in a large 1-gallon zip lock bag. Pour in the marinade, deal the bag and refrigerate for at least 1 hour, ideally longer (up to 24 hours).
  
• When you're ready to cook, use your preferred method: grilling or pan-searing.

Grilled Flank Steak:

• Fire up your gas grill or charcoal grill until it reaches high heat (400 to 500 degrees Fahrenheit). Remove the flank steak from the marinade and allow any excess marinade to drip off. Transfer the flank steak to a hot side of the grill (direct heat). Sear both sides for 6 minutes for medium-rare steak, or until the steak reaches your desired level of doneness.

Pan-Seared Flank Steak:

• Heat a large cast iron skillet (12 inches or larger) over medium-high heat and add enough high temperature cooking oil (such as avocado oil) to generously coat the surface, about 1 to 2 tablespoons. Once the skillet is very hot, remove the meat from the marinade and allow any excess marinade to drip off. Carefully place steak on the hot skillet and sear for 6 to 8 minutes per side, or until the steak reaches your desired level of done-ness.
  

Check the Temperature:

• Use a meat thermometer to check the internal temperature of the steak to ensure you’re achieving just the right temperature according to your preferred degree of doneness. To do so, insert your instant read thermometer into the thickest part of the steak and let it sit until the numbers stop moving.
• Aim for 125 to 130 for medium-rare steak, 135 to 140 for medium and 145 or higher for well-done.

Let the Meat Rest:

• Once the steak has finished cooking, transfer it to a large cutting board and allow it to rest for at least 15 minutes. This gives the juices a chance to distribute throughout the meat and leaves you with a juicy tender steak that is easier to cut.