To make the chimichurri, put the pumpkin seeds, parsley, arugula, oregano, garlic, and salt into a food processor fitted with the S blade. Pulse to break down the herbs and fully incorporate them with the pumpkin seeds.
Add the vinegar and oil. Pulse a few times more. Drizzle in the water with the motor running, until the mixture has reached a desired consistency (you may wish for it to be thinner or thicker--adjust it according to your tastes). Store the chimichurri for up to four days in an airtight container in the fridge.
To make the big green lunch bowl, layer your greens into a generous serving bowl. Arrange all other ingredients on top, and serve, adding an extra sprinkle of pumpkin seeds if desired.