Matzo balls are a type of dumpling made by mixing matzo meal with egg, oil, and seasonings to taste to form a sticky dough which is molded into balls and cooked in a boiling liquid of choice. These filling dumplings are considered by many to be a form of Jewish comfort food, and they are also commonly served at Passover, since they can be made to conform with the dietary rules of Passover. Many Jewish delis sell matzo balls, and they can also be easily made at home; some people make a big batch and freeze them for reheating.
Before plunging into matzo balls, it may help to know something about matzo meal. Matzo meal is derived from matzo, a type of traditional Jewish flatbread which is made from flour and water. The bread is left unleavened to commemorate the flight of the Jewish people from Egypt, when people were unable to allow their bread to rise before cooking it because they were in such a hurry. Unleavened breads are traditionally eaten during Passover and some Jewish people enjoy eating matzo throughout the year.
Matzo is eaten alone at Passover, but it can also be incorporated into recipes. The most common way to use matzo is to grind it up into a coarse meal which is known as matzo meal. The meal is often included as a binder in various dishes, and it makes up the basis of matzo balls.
To make matzo balls, cooks mix matzo meal, salt, pepper, eggs, and oil to form a sticky dough. Other ingredients may be added as well to taste, like onions, although cooks need to be careful to keep their matzo balls Kosher for Passover. The traditional oil of choice is chicken fat, although cooks can use any sort of available oil if they prefer a less fatty version of this classic Jewish food.
Once the dough has been mixed, the cook hand forms it into balls with wet hands to prevent the dough from sticking. The balls are dropped into boiling water or stock and allowed to cook; they naturally fluff up as they cook, and they tend to be dense unless leaveners like baking powder are added. These leaveners cannot, of course, be used during Passover, as leavened foods are not permitted during this Jewish holiday.
The most classic way to eat matzo balls is in matzo ball soup, in which case the dumplings are served in the chicken broth they are traditionally cooked in. Vegetarians can enjoy a variation cooked in vegetable broth, of course.