Prep steak: If the skirt steak comes in a long strip, cut it into 2 or 3 smaller pieces. If using inside skirt steak, cover with plastic wrap and pound with a meat tenderizer or side of a can to tenderize.

Marinate: Whisk the marinade ingredients together in a freezer size Ziploc bag. Add steak, press out excess air and seal. Massage marinade into the steak with your hands through the outside of the bag. Marinate in the refrigerator for 2 to 12 hours.

Let the steaks sit at room temperature for 30 minutes before cooking. Preheat grill to high heat, (550 degrees F with the lid closed). Clean, and grease grill grates with vegetable oil.

Grill steaks for 2-5 minutes per side depending on thickness, or until an internal thermometer reads 130-135 degrees F for medium-rare. The tapered end of the outside skirt will grill the most quickily. Grilling times will vary depending on thickness of your steak so please always use a meat thermometer! (This is the exact one I use.)

Let the steaks sit at room temperature for 30 minutes before cooking. Heat a large cast iron skillet over high heat for 2-3 minutes. Add 2 tablespoons vegetable oil and heat until smoking.

Working in batches as needed, use tongs to carefully add the steak to the pan. Press firmly down with a spatula to ensure full contact. Grill for 2-5 minutes per side depending on thickness, or until an internal thermometer reads 130-135 degrees F for medium rare. Grilling times will vary depending on thickness of your steak so please always use a meat thermometer! (This is the exact one I use.)

Remove the steaks to a cutting board and let rest for 10 minutes before slicing. Slice steaks into thin strips across the grain (perpendicular to the long strands). To do this, place the steaks horizontally in front of you (the grain is running north and south). Slice the steak into sections, then turn the sections 90 degrees, so the grain is running west to east. Hold your knife straight in front of you and slice the steak thinly across the grain.

Using a spatula, combine the pesto and softened butter in a bowl until combined. Serve alongside the steaks if desired.