Step 1

Prepare a grill for medium-high heat. Thread chiles onto skewer and grill, turning often, until charred and softened, about 6 minutes. Let cool; remove stems.

Step 2

Meanwhile, pluck leaves from basil and leaves and tender stems from cilantro and parsley. (You should have about 2 cups of each herb.)

Step 3

Pulse chiles, basil, cilantro, and parsley in a food processor until finely chopped. Add oil, vinegar, and salt and pulse until a thick, slightly textured sauce forms.

Step 4

Do Ahead: Sauce can be made 1 day ahead. Cover and chill. Bring to room temperature before serving.