An etrog is a specific cultivar of Citrus medica, also known is citron. These distinctive almond-shaped fruits have historically been used by the Jewish people during the important festival of Sukkot, also known as the Feast of the Tabernacles. In addition to being used for religious purposes, an etrog can also be used to produce candied citrus peel. These fruits are often readily available in Jewish communities in the weeks leading up to Sukkot, and some greengrocers stock them in other regions for culinary purposes.
In the Jewish tradition, etrog is one of the four species which is traditionally waved during Sukkot ceremonies. The other three species are lulav, hadass, and aravah, known in English as the frond of a palm date, a myrtle branch, and a willow branch. According to tradition, the four species are carefully selected to ensure that they are perfectly formed and beautiful. When selecting the etrog, people look for a symmetrical specimen with its piton, the remnants of the citrus flower, intact.
An etrog which is going to be used at Sukkot must be as even and straight as possible, and ideally it should just be starting to turn yellow. Some people seek out so-called “belted” etrogs which have a narrow region around the middle which gives the fruit an hourglass shape. The fruit is handled carefully, and inspected for scratches and other blemishes which would make the fruit imperfect, and therefore unsuitable for religious ceremonies.
Etrogs are somewhat oblong in shape, with tapering ends and extremely knobbly flesh. They have very thick skins and piths which surround a small, bitter, dry fruit. The flavor and scent of the etrog is probably most similar to that of a lemon, although the actual edible fruit is much smaller. Depending on the region, the fruit may be candied along with the peel.
If you aren’t using an etrog for religious purposes, you can afford to be less meticulous about picking out your fruit. Look for a fruit without any soft spots, discoloration, or signs of mold. The fruits can vary in color from green to yellow, so do not be unduly concerned if you cannot find a bright lemon-yellow etrog. You can keep the fruit refrigerated until use; most people candy it, following the candying directions for other citrus fruits.
If you live in a warm climate, you can grow etrog outdoors; the fruit typically grows in USDA zones 10 and 11. Keep the fruit tree in a warm place well insulated from winds, and do not overwater it. It takes around three years for an etrog cutting to mature enough to grow fruit, and around seven years for an etrog grown from seed to grow fruit.