Wash the spinach well. Cut the leaves away from the stems, discarding the stems, and chop the leaves into 1-inch strips. Wash the arugula and discard the stems. If the arugula leaves are large, chop them as well. If you're using baby spinach and arugula, you can skip this step.
Heat the oil in a skillet over medium heat. Stir and cook the onion, garlic and chile, if using, for 5 to 10 minutes, until the onion is translucent. Add the spinach and arugula, continuing to cook and stir until the leaves are wilted and shrunk. Stir in the cilantro. Season with vinegar and salt.
Lightly oil in a 9 x 13-inch baking dish. Spread about 1/2 cup of green enchilada sauce in the bottom.
Pre-heat oven to 350°. Place tortillas on baking sheets, 4 to 6 tortillas to a pan. Lightly brush or spray both sides of the tortillas with oil. Bake about 5 minutes, until pliable. (see note)
Spread a heaping tablespoon of the greens in a tortilla. Sprinkle about the same amount of cheese on top. Roll the tortilla around the filling and place it seam side down in the baking dish. Repeat with the rest of the tortillas. You can cover the pan at this point and refrigerate overnight.
Pour green sauce over the rolled tortillas, making sure to coat the ends. Sprinkle with more cheese, if you wish.
Bake until heated through, about 20 minutes. Sprinkle with some chopped cilantro and parsley.