Place the vinegar, mustard, and garlic in the bowl of a food processor. Pulse a few times to break up the garlic. Add all the herbs and pulse until the herbs are evenly chopped. Use a spatula to scrape down the sides of the bowl, then add the olive oil. Pulse until the herbs are coarsely chopped and a thick sauce forms. (For a thinner sauce, stir in additional oil.) Taste, adding salt if desired.
Store in an airtight container in the refrigerator for up to 1 week.
Notes
No food processor or blender?
Make these green sauces directly on a cutting board. Roughly chop the garlic with the Dijon mustard, add the herbs, and chop to reach the desired consistency. Transfer to a small bowl and pour in the oil, then stir with a spoon to incorporate. Season with salt and serve.