Olive oil is expensive enough that it should be properly looked after. Some people don't realize that left in the light it will quickly go rancid.

• Store it in dark cook place.
• It's a waste of money using extra virgin olive oil (that chefs refer to as Evoo) to cook with. Add it at the finish for flavor.
• And you're watching your pennies, buy a really good extra virgin olive oil in a small bottle and make your vinaigrette with a flavorless vegetable oil like peanut oil (if you're not allergic) and add a tablespoon of the good Evoo at the end.

Litteri's, Washington's oldest Italian grocery, a dark and mysterious emporium at 57 Morse St NE, 202 544 0183, has a good, reasonably priced stock of olive oils, among other treasures. But check the sell-by dates on their olive oils. They've been known to be offered past their best.

Cleveland Park Liquor & Wine often stocks particularly good olive oils and vinegars.

For Kosher cold-pressed extra-virgin olive oil pressed in Israel from varieties as old, its producers say, as the Bible, call Grace's Marketplace in New York, 212 737 0600. Souri is filtered and mellow, Barnea is unfiltered and more complex in flavor.