Assuming you don't cheap out
and buy it at your local supermarket
, assuming you can do that, here is a recipe to make it yourself:
1. Cut garlic
clove into halves and rub the cut sides over the inner surface of a small bowl. Reserve the garlic.
2. Whisk mustard and vinegar together in the bowl. Season with salt and pepper to taste.
3. Dribble oil into the bowl in a slow steady stream, whisking constantly, until dressing is creamy and thickened and all the oil has been incorporated.
4. Taste and correct seasoning. Add reserved pieces of garlic; cover the bowl and let the dressing stand at room temperature until you need it. Remove garlic and rewhisk the dressing if necessary before using.
Makes 1 1/4 cups.