The day before cut the Skirt Steak (1 pound) in half with the grain. Hold your knife at a slight angle and slice each piece of steak into strips. The angle creates wider strips.
Place Italian Flat-Leaf Parsley (1 bunch), Fresh Cilantro (1 bunch), Sweet Onion (1/2) and Garlic (4 clove) in large bowl and add Red Wine Vinegar (3 tablespoon), Kosher Salt (1 teaspoon), Salt (1 pinch), Ground Black Pepper (1/2 teaspoon) and Crushed Red Pepper Flakes (1/2 teaspoon).
Slowly drizzle Olive Oil (3/4 cup) while stirring. Taste mixture and add Caster Sugar (1 pinch) to balance. Adjust seasonings if needed. Allow sauce to set in refrigerator for a couple hours before using
Season the strips of skirt steak with Salt (to taste) and Red Chili Pepper (to taste). Place the strips into a large ziplock storage bag and add half of the chimichurri sauce. Place the bag in the refrigerator over night (at least 4 hrs).
Soak some wooden skewers in water for about an hour to prevent burning. Remove the skirt steak strips from the marinade and thread onto the skewers. While the steak is coming up to room temp, Prepare a charcoal grill for direct grilling.
Grill each skewer to medium internal about 3 min on each side for a total of 6min or until desired doneness. Serve and enjoy.