In the winter, it's the vinaigrette that counts most in a salad. Summer's abundant, vine-ripened tomatoes and fine farm-fresh produce are long gone, so the flavor of a fine vinaigrette becomes more important.

Fortunately, there's no secret to making a great vinaigrette. Anyone who can stir some oil, vinegar, salt and pepper together can do it. What's important is that you choose the right oil and the right vinegar, and that you mix them in the right proportions.

Olive is the best oil for making a vinaigrette. Recently I tasted four extra-virgin olive oils that ranged in price from $5.88 to $13.99 for a half-liter bottle and in color from crystal-clear golden yellow to a cloudy grayish green. They were all fine, fruity oils, and the more expensive had subtle complexities of taste that the less expensive ones did not possess, but the least expensive was the one I liked best for all-around cooking and vinaigrette making. Its full, round flavor and brilliant yellow color made it ideal for vinaigrettes since the flavor of the vinegar competes with and often destroys the subtleties of expensive oils.

I also tasted three different types of vinegar. The first was a dark, almost black balsamic (madeira-based) vinegar that was so rich and sweet you could almost drink it alone. Next was a tawny-colored sherry vinegar that was more acidic than the balsamic vinegar, but still had a sweet edge to it and a fine full-flavored sherry aftertaste. Here were two extraordinary good, full bodied, but very different tasting vinegars to add to my winter cupboard -- and they were fairly inexpensive, too (22 and 15 cents per ounce, respectively).

Next, I tasted a great tarragon vinegar -- the vinegar was clear in color, the bottle filled with sprigs of fresh tarragon, the vinegar sweetly aromatic and not too acidic (though considerably more acidic than the balsamic and sherry vinegars). The tarragon vinegar was a competitive 23 cents an ounce (vinegars come in so many sizes that comparisons can only be made by the ounce). However, this was a 35-ounce bottle and seemed like a lifetime supply (who wants to look that far ahead with vinegar?), but it was certainly the best tarragon vinegar I have ever tasted.

Some people like a very sharp vinaigrette, others like only the barest hint of acidity, but a good rule of thumb among vinaigrette aficionados is 4 to 5 parts oil to 1 part vinegar. Mix and taste as you go. With a sweet, only very mildly acidic balsamic vinegar you might want to start with a 3 to 1 ratio, while with an inexpensive commercial red wine vinegar you might want as much as 6 parts oil to one part vinegar.

Once you've invested a little time and money into buying and tasting some oils and vinegars and found the ones you like best, then all you need to do is to combine them and stir in a little salt (I use very little) and some freshly ground black or white pepper (I use black, and a lot of it). Especially during the winter, being a little heavy handed with the pepper adds an unexpected hint of "hotness" to the vinaigrette that gives this simple concoction a new dimension.

Here are three very different-tasting vinaigrettes, with suggestions for the kinds of salads they should dress: BALSAMIC VINAIGRETTE (Makes 1 cup)

This is an extraordinary dressing for salads made of marinated green beans, for salads made from sweet bell peppers, and for salads that have fruit in them.

3/4 cup fine fruity olive oil

1/4 cup balsamic vinegar

1/8 to 1/4 teaspoon salt

1/4 to 1/2 teaspoon freshly ground black pepper

Mix ingredients and serve. SHERRY VINAIGRETTE (Makes 1 cup)

This is best with very simple green salads, such as a salad of bibb and romaine -- where the flavors of the oil and the vinegar are almost more important than the leaves onto which they cling.

3/4 cup full-bodied, complex olive oil with a lingering aftertaste

3 tablespoons sherry wine vinegar 1/8 to 1/4 teaspoon salt

1/4 to 1/2 teaspoon freshly ground black pepper

Mix ingredients and serve. TARRAGON VINAIGRETTE (Makes about 1 cup)

Use with a deceivingly simple-looking salad of boston lettuce and julienned sticks of cucumber and celery, or with boston lettuce and a little watercress for contrast in color and flavor.

1 cup fine fruity olive oil

3 tablespoons excellent quality tarragon vinegar

1/8 to 1/4 teaspoon salt

1/4 to 1/2 teaspoon freshly ground black pepper

Mix ingredients and serve.