For frying foods well seasoned with onions, garlic, or herbs, such as potato latkes, I use olive oil. It doesn’t taste like the traditional schmaltz, but like schmaltz, it does have a rich, flavorful taste that enhances foods. And, after all, it was olive oil that burned in the lamp for eight days in the Temple—not chicken fat. In dishes where the taste of olive oil is important, as in the Green Olive Sauce, I use an excellent quality extra virgin oil.

I often turn to canola oil for its high smoke point and mild taste, especially for high-temperature frying, particularly when it comes to moist foods like New Mexican Sweet Potato Latkes or Italian Apple Fritters.

I also use other fine vegetable and nut oils: the toasty popcorn flavor of unrefined com oil for a more nuanced mamaliga (Romanian corn meal mush), also marvelous for American corn bread and muffins; a delicate sunflower or sesame oil when a light touch is required in a nondairy dish; or even better, avocado oil, which imparts a wonderful buttery taste to food and is excellent for frying. To prevent butter from burning at high temperatures, I often combine it with a little avocado oil. (Most people think the cholesterol content of avocado oil is astronomical. They are wrong: its cholesterol content is zero. Its price, however, can be astronomical.) Another option for frying dairy foods is ghee, the Indian equivalent of clarified butter, available commercially in many specialty stores with kosher certification. Melted ghee is also excellent for brushing phyllo sheets.

Pricey—but worth it—fragrant nut oils, such as walnut or hazelnut, make stellar salad dressings and are particularly appealing in baking with nondairy ingredients, when using butter would render the dish inappropriate for a meat meal.

Because I don’t use these delicate oils as frequently as I do olive oil, after opening I store them tightly sealed in the refrigerator, where they will keep for months. Any cloudiness or congealing disappears when the oil returns to room temperature. These oils are available in health food and specialty shops, as well as many well-stocked supermarkets.

For dairy dishes, I always use sweet (unsalted) butter. Despite the ads, no margarine will ever taste as good as pure butter. Besides, margarine contains as many calories as butter, and processing techniques and preservatives render any benefits garnered from the reduced cholesterol levels questionable at best.