Written by Rabbis Eli Gersten, Yaakov Luban, and Moshe Zywica of the Orthodox Union
Halacha! The Shulchan Aruch (OC 167: 5) says not to recite Hamotzi until condiments or salt are brought to the table. Why? So the challah can be dipped right after the beracha is recited. The Mishnah Berurah (167:27) explains that dipping in salt or condiments makes the first bite tasty and adds honor to the beracha.
What if the bread needs no taste enhancement? Then the Shulchan Aruch says that condiments are not required. The Rema disagrees in that it is a mitzvah to have salt on the table.
The table is similar to the mizbeyach (altar) in the Beit Hamikdash, and there was a positive commandment to salt the karbanot (sacrifices) on the mizbeyach. Additionally, the Midrash relates that since we cannot speak words of Torah at the table until we eat the first bite of bread, this period of silence presents an opportunity to negate the evil that angels speak against us (chas v’shalom). Having salt on the table invokes the memory of the covenant of salt (ie. all karbanot are offered with salt), and in this merit we are protected.
According to the Rema, the salt must be on the table, but the bread does not have to be dipped in the salt. Nonetheless it is customary to dip the bread in salt, in accordance with the writings of mekubalim (Mishnah Berurah ibid 33 and Aruch Hashulchan 12).