Oranges are a citrus fruit that grows in warm, sunny climates (Arizona, Florida, Texas, and California in the U.S. The sweet orange family, which is the most common form of the fruit, includes common or blond oranges like Valencias; navels; and blood oranges. Then there are all the relatives: mandarins, distinguished by loose, easy-to-peel skin and flowery flavor (tangerines are a type of mandarin); temple oranges and clementines (crosses between oranges and mandarins); and tangelos (hybrids of mandarins, oranges, and grapefruit). Bitter oranges, such as the Seville, are too bitter to eat out of hand and instead are used to make marmalades; their peel is prized for candying, and their essential oils flavors foods and booze, such as Curacao. Almost every part of the fruit is usable in the kitchen: the flesh, the juice, and the aromatic skin. Only its pits and the spongy white pith between the skin and the flesh are not of use.
1 medium = 6 to 7 Tbs. juice and about 2 Tbs. lightly packed zest if grated on a rasp-style grater
Here's what you need to know as a cook: Valencias are good all-purpose oranges because they're juicy, they have good flavor, and their rind, flesh, and juice of have a nice, deep color. Blood oranges contribute an exotic look to salads or other dishes. They're less acidic than navels and Valencias, which can make them seem sweeter. The flesh and juice of navels are delicious but can turn bitter when exposed to air, so these are best eaten out of hand or served soon after peeling. Fruits labeled as "juice oranges" produce copious amounts of juice and have flavorful zest, but they're often seedy, pulpy, and messy when sliced. Oranges are in season in the winter in the United States. Choose that feel heavy for their size (signaling they're juicy) with a skin that does not feel loose.
Orange zest adds a floral, citrusy accent to dishes and may be removed using a grater, a peeler, or a zester. Zest the fruit before peeling or juicing.
Oranges are fine if stored at room temperature for a few days, but they'll last longer and taste better if refrigerated.