Instructions: My yogurt epiphany came in one of Chicagos most popular Greek restaurants.

There on the meze platter with the familiar hummus and tabbouleh was tzatziki, a creamy salad of yogurt, cucumber and herbs that took my breath away. The yogurt was thick and tangy, like sour cream with a kick. It married the cucumber, garlic, mint and dill into a soothing yet flavor-packed dish unlike any I had ever experienced.

I couldnt get over the fact that the key ingredient in tzatziki was yogurt.

It was light-years removed from the thin, sour stuff I made in my brown rice and granola days and bore little resemblance to the cloying, fruit-flavored yogurt in little plastic cups that so many people pack in their lunches.

After that eye-opening Greek dinner, I began looking for ways to capitalize on yogurts unique character in my own cooking.

Id always known that this milk product, fermented with friendly bacteria, was healthful, high in calcium and protein, and good for the digestion. I considered those its only recommendations. But yogurt prepared with care, I soon learned, brings a velvety texture and lemon undertones to many a recipe.

Middle Eastern and South Asian cooks long have recognized its virtues. Yogurt is believed to have originated in the neighboring Balkans thousands of years ago, and people throughout the region depend on it as the linchpin of dishes as varied as Turkish yogurt soup with rice and Indian tandoori chicken.

Here in the United States - where fear of fat is almost universal - most cooks still think of reduced-fat yogurt as a lean substitute for sour cream, buttermilk, cream cheese or mayonnaise in traditional baked goods, dips and sauces. And it is a terrific substitute for mayonnaise in the base of a baked-chicken recipe given me by a friend.

One can go too far, however, and turn out a pallid imitation of an otherwise excellent recipe by paying more attention to fat than flavor. I ruined the texture of a much-loved sour cream coffee cake from an old edition of Joy of Cooking by using low-fat yogurt in the place of sour cream, which provided almost all of the fat in the recipe. Yet low-fat yogurt contributed just the right spark to another favorite, lemon blueberry coffee cake, which also calls for a cup of butter and three eggs. Fat, Id learned by then, plays an important role in making baked goods tender.

Still, Im more interested in taking advantage of yogurts essential nature: rich and smooth and thick. Since Im struggling with high cholesterol, low-fat is better. Yet low-fat and non-fat yogurt can be thin and uninspiring in dips and spreads. Thats where yogurt cheese enters the picture.

Drained of excess liquid, yogurt develops a consistency similar to a soft cream cheese while retaining its lively tang. This is the secret to tzatziki as well as the foundation of a satiny, cheesecake-like tart. Salted, its known as labaneh in much of the Middle East, and is a traditional component of the meze platter.

In a misguided attempt to make yogurt cheese sound hip and sell cookbooks, authors David and Nikki Goldberg have dubbed it YoChee. Dont let the cutesy name deter you from trying it.

Yogurt cheese works quite well as a substitute for cream cheese in many American recipes. Ive also beaten it into garlic mashed potatoes and traded it for much of the oil in a creamy salad dressing with good results. And it makes a nice spread for bagels.

Still, even after all that experimenting, tzatziki remains my favorite yogurt cheese recipe. It takes very little active work and produces a flavorful dish that can serve as a party dip with flat bread or wedges of pita bread or as a side dish with barbecued meats.

The labaneh also is a hit, particularly when made with whole-milk yogurt.

Even then, its fat content is less than a fifth of the same amount of cream cheese. To serve as a meze, mound the cheese on a plate, drizzle with olive oil and sprinkle with zaatar, a combination of dried herbs and sesame seeds that can be found at the Middle Eastern grocers now common in Silicon Valley.

Whole-milk yogurt also is recommended for Deborah Madisons elegant Brown Sugar-Yogurt Tart. But I made a very successful version with low-fat yogurt that I had drained for 24 hours, until it was very thick. The creamy custard set off the nutty crust, and the citrus edge of the yogurt sparked hints of molasses in the brown sugar.

Yogurt, it turns out, can be both healthful and indulgent at the same time.

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