First, make the chimichurri sauce. In a food processor, combine the parsley, cilantro, avocado, garlic and lime juice or vinegar. Process, stopping to scrape down the sides of the container once or twice. With the machine running, slowly stream in the olive oil and water. Season with red pepper flakes, salt and pepper, and process again to blend well. Use a spatula to transfer the sauce to a small bowl and cover it.