1. In a large resealable plastic bag (or a large mixing bowl) add all the ingredients for the marinade and toss to combine.
2. Cover and marinate in the fridge for 2 hours up to 8 hours.
3. Prepare the chimichurri sauce: Add the cilantro, parsley, garlic, salt, cumin, and red pepper flakes to a food processor. Pulse until the leaves are coarsely chopped. Add the red wine vinegar and the olive oil, pulse 5 times. The chimichurri sauce should be emulsified and the herbs coarsely chopped. Transfer the chimichurri sauce to a medium bowl. Cut the avocado into 1/2-inch dice. Add the avocado to the chimichurri and gently stir to combine. Cover and refrigerate until ready to use.
4. Preheat grill to high heat. If cooking indoors, heat your grill pan or cast iron skillet.
5. Remove steak from marinade and season both sides with salt + pepper. Set prepared steak directly on grill and cook for 3-4
minutes without touching. Turn and cook for one more minute if using a flat iron steak and 3-4 minutes if cooking a sirloin. You want your steak temperature to be medium well. Allow to rest while cooking onions and peppers. Optional to tent the steak with foil to keep warm
6. On the stove heat a cast iron skillet to high heat. Add olive oil, onions, peppers, green chilies, jalepenos and a tablespoon of taco seasoning cooking until slightly charred, stirring often.
7. Thinly slice the steak and serve overtop warm vegetables, top with avocado chimichurri and warm tortillas. Optional to serve alongside
some other toppings like sour cream, salsa or shredded cheese and hot sauce!