Prepare the following, adding each to a food processor fitted with the blade attachment or a blender as you complete it: Coarsely chop the leaves and tender stems of 2 medium bunches fresh parsley and 2 medium bunches fresh cilantro until you have 2 packed cups of each. Coarsely chop 1 bunch fresh chives until you have ¼ cup.
Add 3 large or 4 small peeled garlic cloves, ¼ cup plus 2 tablespoons extra-virgin olive oil, 3 tablespoons sherry vinegar, 2 teaspoons ground cumin, and 1 teaspoon kosher salt. If using a food processor, process the mixture (if using a blender, do long pulses instead), stopping and scraping down the sides of the bowl or blender jar as needed, until the garlic and herbs are very finely chopped and the texture is like pesto, 2 to 3 minutes. Taste and season with more kosher salt as needed.
