Lentils are the traditional New Year's Eve dish associated with prosperity in Italy because their round shape resembles coins.
They are commonly served with cotechino, a seasoned pork sausage, or with zampone, a stuffed pig's trotter. The pairing is especially associated with the New Year because pork symbolizes abundance and lentils symbolize money or wealth.
The custom is widespread but not identical in every Italian region or household. Recipes and serving traditions vary, and some families eat the dish on New Year's Day rather than precisely at midnight.
Lentils are not a literal promise of financial success. Their symbolism comes from appearance and the broader European tradition of treating plentiful foods as signs of good fortune at the start of a new year.