Shake all of the ingredients together in a jar with a tight-fitting lid. The dressing can be refrigerated; bring to room temperature, then shake vigorously to recombine before using.

Alternatively: Mash the garlic with the back of a knife, sprinkle the garlic with the salt and continue to mash with the knife, scraping it back and forth over the garlic until a fine paste is formed. Add to a heavy bowl. Stir in the balsamic, onion or shallot, Dijon, and pepper.  Slowly drizzle in the oil, almost drop by drop, stirring briskly with a whisk or fork. When the mixture begins to thicken, continue adding the oil in a small stream, all the while still stirring briskly. The emulsion will last for some time, but will eventually separate.

Dressing improves if it sits for a bit before using.

Nutrition: Per Serving: 91 Calories; 10g Fat (97.9% calories from fat); trace Protein; trace Carbohydrate; trace Dietary Fiber; 0mg Cholesterol; 75mg Sodium.  Exchanges: 0 Grain(Starch); 0 Lean Meat; 0 Vegetable; 0 Fruit; 2 Fat; 0 Other Carbohydrates.