Pat the steak dry with a paper towel and place it in a large, shallow dish.

Add the parsley, cilantro, garlic, lemon juice, oregano, and red pepper flakes to the bowl of a food processor.

Pulse until finely chopped, about 10-15 seconds.

With the processor on low, slowly add in the olive oil and pulse until it is well combined.

Season with salt and pepper to taste.

Add 1/4 of the chimichurri over the raw steak, reserving the rest to top the steak after it has been cooked.

Allow the steak to marinate for 15 minutes at room temperature.

Preheat your grill to medium high heat.

Remove the steak from the marinade and add to the preheated grill.

Grill for about 3-4 minutes per side based on the thickness of the flank steak.

Let the steak rest for 5 minutes after grilling.

Slice and serve with remaining chimichurri sauce.