I made this with lemon juice rather than vinegar (had some lovely lemons that Brian sent from Arizona) and I found that the recipe needed the added acidity from the vinegar. I like a very acidic dressing, so adjust to taste.
1 small shallot, minced (about 2 tablespoons)
1 small clove garlic, minced (about 1/2 teaspoon)
2 teaspoons Dijon mustard
3 tablespoons white wine vinegar
1 tablespoon water
3/4 cup extra-virgin olive oil
Kosher salt and freshly ground black pepper
Recipe
You can mix this like a traditional vinaigrette (i.e. in a bowl, drizzling in the oil) or just shake everything but the salt and pepper up in a Mason jar - then taste and add salt and pepper, as necessary. I chose the jar method.
Vinaigrette will keep in the refrigerator for up to 2 weeks.