Of all the times that various cultures observe the new year—January 1 on the Gregorian calendar, late winter on the lunar calendar, or early fall on the Jewish calendar—I think the one that makes the most sense is Nowruz, the Iranian new year, celebrated at the Northern Hemisphere's spring equinox. Nothing says "new start" like the first buds of leaves growing on trees or the return of animals from hibernation, at least in those places with distinct seasons.
This year Nowruz falls on March 20, at 9:32:13 p.m. (Tehran time), to be precise. Recently the United Nations passed a resolution recognizing March 21 as the "International Day of Nowruz." The observance dates back to ancient Zoroastrian tradition, and is also celebrated in many of the countries of Central Asia that were once part of, or influenced by, the Persian Empire. Because it predates Islam, its observance has sometimes been controversial. The Taliban banned it in Afghanistan before 2001, and just this week, Iranian officials denounced the ancient fire festival, Chaharshanbeh Suri, traditionally held on the eve of the Wednesday before the new year.
While jumping over bonfires is probably the most exciting element of the festivities, food also holds an important place in both Chaharshanbeh Suri and Nowruz celebrations. Ajeel, a mix of seven nuts and dried fruits, is distributed. (Seven is a significant number in Persian mythology.) Ash-e Reshteh is a noodle soup that is said to bring good luck, and is eaten whenever starting something new.
Spring foods, especially fresh herbs, are featured prominently in Nowruz dishes such as sabzi polo va mahi, herbed rice with fish. Fresh herb kuku is a fluffy omelet that incorporates lots of herbs plus another symbol of spring, eggs. Decorating eggs, much like Easter eggs, is also a traditional part of the celebration.
A few weeks before Nowruz, people begin sprouting lentils, wheat or barley seeds, called sabzeh. By the holiday the seeds or legumes will have shoots several inches long, providing a powerful symbol of rebirth.
The sabzeh is then used for the sofreh haft sin, an arrangement of (at least) seven symbolic items that begin with the letter "s" (or, sometimes, the letter that corresponds to the "sh" sound in English), which is an essential element of the celebration. Like many traditions with ancient roots, the original significance of the haft sin is difficult to nail down. For instance, I haven't been able to find out why the items must begin with "s"—if anyone out there can tell us, please comment below. One of the clearest explanations I have found is that the seven items correspond to the seven stages in which the material world was believed to have been created.
Aside from the sabzeh, these items include lotus fruit (senjed), symbolizing love; apples (sib), symbolizing health; a sprouted wheat pudding called samanu, symbolizing sweetness and fertility; vinegar (serkeh), which signifies age and patience (traditionally, wine—sharab—was used, but alcohol is not permitted in Islam); sumac berries (somagh), which either represent the color of sunrise, when good triumphs over evil, or the "spice of life"; and garlic (seer), a symbol of medicine. Additional items, some starting with "s" and some not, are also often included.
Many people also serve one of my favorite s-words: sweets, like this Persian pistachio nougat, flavored with rose water.