Vinaigrette is one of the simplest and most versatile salad dressings available. At its heart, it is nothing more than an emulsion of oil and vinegar seasoned with salt, pepper and whatever herbs or aromatics you enjoy. From this simple base, create any number of thickened vinaigrettes to suit your taste, mood and the salad you are making. Choose a thickening method based on how dense you want the dressing to be and what flavors you enjoy.
Do Things Differently
If you want a classic vinaigrette that is only slightly thicker than usual, combine all of the ingredients in your blender instead of whisking them to create the emulsion. The blades in the blender break up the fat and water into smaller droplets than a whisk can, creating a smoother emulsion that feels thicker on the tongue. If you enjoy the texture of diced shallots or garlic in your vinaigrette, stir them in by hand after the blending process or they will be pulverized by the blades.
Thicken by Reduction
Balsamic vinegar is a dark, syrupy vinegar traditionally made in Modena, Italy. It is made from grape juice that is boiled down, or reduced, then fermented and aged. Because of this reduction, balsamic vinegar is significantly thicker than other vinegars and will produce a thicker vinaigrette. If you want to thicken your vinaigrette even more, use a balsamic reduction, or glaze. Boil bottled balsamic vinegar to evaporate some of the liquid and concentrate the flavor of the vinegar.
The Great Emulsifier
Vinaigrette is an emulsion that combines oil with vinegar. A classic vinaigrette uses the physical whipping action of the whisk to force the vinegar and oil molecules to combine. If you add a spoonful of honey or dijon mustard to the vinaigrette, It will assist in the emulsification process and thicken the vinaigrette with less vigorous whisking.
Go All the Way
If you want to take your thick vinaigrette over the top, make it into a creamy dressing. Whisk in heavy cream, crème fraîche or plain yogurt until it is as thick and creamy as you want it. Go slowly to avoid breaking the emulsion, and taste frequently to determine whether you need to adjust the seasonings. The ultimate emulsifier is an egg yolk, which - when the vinaigrette is beaten into it slowly - thickens the dressing to the consistency of mayonnaise, which is essentially what it becomes. You can thin it to a pourable consistency by adding liquid.