How to Make It
Finely grind fennel seeds, cumin seeds, and coriander seeds in a mortar and pestle or spice grinder; set ground spices aside.
Combine cilantro, basil, garlic, and oil in a blender; process until smooth, about 30 seconds. Transfer to a bowl, and stir in vinegar, salt, and ground spices. Cover and chill immediately to keep the vibrant green color. (If making a day ahead, wait to add the vinegar until ready to serve.)