To make the chimichurri sauce, combine parsley, cilantro, oregano, shallot, chili and garlic in the bowl of a food processor; season with salt and pepper, to taste. With the motor running, add olive oil and red wine vinegar in a slow stream until emulsified; set aside 1/2 cup of the mixture in the refrigerator until ready to serve.
In a gallon size Ziploc bag or large bowl, combine steak and remaining parsley mixture; marinate for at least 4 hours to overnight, turning the bag occasionally. Drain the steak from the marinade.
Preheat oven to 425 degrees F. Line a baking sheet with parchment paper.
In a large bowl, combine potatoes and olive oil; season with salt and pepper, to taste.
Place potatoes in a single layer onto the prepared baking sheet.
Place into oven and bake for 25-30 minutes, until golden brown and crisp, stirring and rotating pan halfway through baking.
Preheat grill to medium high heat. Using paper towels, pat both sides of the steak dry; season with salt and pepper, to taste.
Add steak to grill, and cook, flipping once, until desired doneness, about 6 minutes per side for medium rare. Let rest 5 minutes.
Thinly slice steak against the grain and serve with reserved 1/2 cup parsley mixture and potatoes.