Both fresh cilantro and dried coriander seed are used to season a variety of dishes. Coriander seeds are spherical and have a tart-spicy to sweet-aromatic flavor. The seeds are often ground and used as a spice. Coriander seeds taste particularly savory if they are first toasted briefly and then ground, or crushed in a mortar. Ground coriander does not have a long shelf life because it contains a high proportion of essential oils.
From Wikipedia: “Coriander (UK: /ˌkɒrɪˈændər/; US: /ˈkɔːriˌændər/ or /ˌkɔːriˈændər/; Coriandrum sativum), also known as cilantro (/sɪˈlɑːntroʊ/) or Chinese parsley, is an annual herb in the family Apiaceae. All parts of the plant are edible, but the fresh leaves and the dried seeds are the parts most traditionally used in cooking.”
“All parts of the plant are edible, but the fresh leaves and the dried seeds are the parts most traditionally used in cooking. Coriander is used in cuisines throughout the world.”
Leaves: “The leaves are variously referred to as coriander leaves, fresh coriander, dhania, Chinese parsley, or cilantro. ...
The leaves have a different taste from the seeds, with citrus overtones. Some people may be genetically predisposed to find the leaves to have unpleasant soapy taste or a rank smell. ... The leaves spoil quickly when removed from the plant, and lose their aroma when dried or frozen.”
Fruits: “The dry fruits are known as coriander seeds. The word "coriander" in food preparation may refer solely to these seeds (as a spice), rather than to the plant. The seeds have a lemony citrus flavour when crushed, due to the terpenes, linalool, pinene, and limonene, among others. It is described as warm, nutty, spicy, and orange-flavoured.
The variety C. s. vulgare has a fruit diameter of 3–5 mm (0.12–0.20 in), while var. C. s. microcarpum fruits have a diameter of 1.5–3 mm (0.06–0.12 in). Large-fruited types are grown mainly by tropical and subtropical countries, e.g. Morocco, India, and Australia, and contain a low volatile oil content (0.1-0.4%). They are used extensively for grinding and blending purposes in the spice trade. Types with smaller fruit are produced in temperate regions and usually have a volatile oil content around 0.4-1.8%, so are highly valued as a raw material for the preparation of essential oil.”
Roots: “Having a deeper, more intense flavor than the leaves, coriander roots are used in a variety of Asian cuisines, especially in Thai dishes such as soups or curry pastes.”
“Coriander is commonly found both as whole dried seeds and in ground form. Roasting or heating the seeds in a dry pan heightens the flavour, aroma, and pungency. Ground coriander seed loses flavour quickly in storage and is best ground fresh. Coriander seed is a spice in garam masala and Indian curries which often employ the ground fruits in generous amounts together with cumin, acting as a thickener in a mixture called dhana jeera.
Roasted coriander seeds, called dhana dal, are eaten as a mouth refresher and digestive. They are the main spice in the south Indian dish sambhar.
Outside of Asia, coriander seed is used widely in the process for pickling vegetables. In Germany and South Africa (see boerewors), the seeds are used while making sausages. In Russia and Central Europe, coriander seed is an occasional ingredient in rye bread (e.g. Borodinsky bread), as an alternative to caraway.
The Zuni people of North America have adapted it into their cuisine, mixing the powdered seeds ground with chile and using it as a condiment with meat, and eating leaves as a salad.
Coriander seeds are used in brewing certain styles of beer, particularly some Belgian Witbier. The coriander seeds are used with orange peel to add a citrus character.
Coriander seed is one of the main traditional ingredients in the South African Boerewors, a popular spiced mixed-meat sausage.”
“The nutritional profile of coriander seeds is different from the fresh stems or leaves. Leaves are particularly rich in vitamin A, vitamin C and vitamin K, with moderate content of dietary minerals. Although seeds generally have lower content of vitamins, they do provide significant amounts of dietary fiber, calcium, selenium, iron, magnesium and manganese.”
“One preliminary study showed coriander essential oil to inhibit Gram-positive and Gram-negative bacteria, including Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, and Escherichia coli.”
Flavor and aroma:
“Different people may perceive the taste of coriander leaves differently. Those who enjoy it say it has a refreshing, lemony or lime-like flavor, while those who dislike it have a strong aversion to its taste and smell, characterizing it as soapy or rotten. ... In a genetic survey of nearly 30,000 people, two genetic variants linked to perception of coriander have been found, the most common of which is a gene involved in sensing smells. ... Flavor chemists have found that the coriander aroma is created by a half-dozen or so substances, and most of these are aldehydes. Those who dislike the taste are sensitive to the offending unsaturated aldehydes, while simultaneously may also be unable to detect the aromatic chemicals that others find pleasant. Association between its taste and several other genes, including a bitter-taste receptor, have also been found.”