Whisk all ingredients together in small bowl. Place the skirt steak in a sealable plastic bag or air-tight container, followed by marinade.
Seal the bag tightly, squeezing out as much air as possible. Gently knead the bag to ensure steak is well-coated by marinade.
Place in the fridge to marinate at least 30 minutes, ideally between 6-20 hours.
Remove steak from bag and place on platter to bring to room temperature. Grill and serve to your liking.