Add all of the ingredients for the skirt steak marinade to a small bowl or blender and whisk or blend until combined. 

Transfer the raw skirt steak to a large 1-gallon zip lock bag along with the marinade. Seal the bag then swish everything together until the steak is well-coated with marinade.

Refrigerate for at least 8 hours, up to 48 hours. This may seem like a long period of time, but trust me, it’s worth it. The longer the beef marinates, the more tender it will become and the more flavor that will be injected into the meat.

Before cooking, remove the skirt steak from the marinade and allow any excess marinade to drip off.

Heat up your charcoal or gas grill until it is very hot (400 to 500 degrees). Place the skirt steak over direct heat and grill for 6 minutes per side for medium-rare steak or until it reaches your desired level of doneness.

Heat a large cast iron skillet (you will need a 12-inch skillet to fit a 1.5 to 2 pound skirt steak) over high heat and add enough avocado oil or olive oil to generously coat the surface. Allow the skillet to heat up until it is sizzling hot. Carefully place the steak on the hot skillet and sear for 6 minutes per side for medium-rare steak or 8 minutes per side for medium steak (or to your desired level of doneness).

Transfer the cooked steak to a cutting board and allow it to rest for at least 15 minutes before slicing. Use a sharp knife to slice against the grain of the meat.