½cupchopped green olives such as Castelvetrano (optional)
Red pepper flakes (optional)
Make the Scallion Chimichurri sauce: Place the scallions, parsley, oregano, ½ cup olive oil, vinegar and salt and pepper in a food processor and blend until fairly smooth (or as smooth as you like it) and well combined.
Place the asparagus on a rimmed baking sheet, drizzle with the remaining tablespoon oil and sprinkle lightly with salt.
Meanwhile, preheat the grill, the broiler, or a grill pan. Transfer the asparagus to the grill or the grill pan and cook for about 4 to 6 minutes, turning frequently, until they are browned in spots and crisp tender. If you are broiling the asparagus, keep them on the rimmed baking sheet and broil, flipping them midway during cooking, for the same amount of time.
Transfer the asparagus to a serving platter. Spoon some of the chimichurri sauce over the asparagus, and pass the rest of the side. Top with the olives, if using, then sprinkle with the red pepper flakes if desired. Serve hot, warm or at room temperature.