Brochas: Daf Mem amud aleph

Rava bar Shmuel said in the name of R. Chiya, the one who breaks the bread is not permitted to (recite the blessing) and break the bread until they being salt and relish before each an every person.  Rava bar Shmuel visited the home of the Reish Galusa. They brought out bread for him and he (immediately) broke it (without waiting for salt or relish).   They asked, did Master retract his teaching? He said to them, this bread (because it has been made with refined flour and is therefore quite tasty - Rashi) does not require one to wait.

Tosfos comment that on refined bread such as ours (or bread which is tasty or itself contains salt) one is not required to wait for salt; however, R. Menachem was scrupulous based on a Medrash which says that guests while waiting for their host to break bread, post having washed their hands, are bereft of mitzvos and susceptible to the accusations of the "Saton." Having salt on the table acts as a shield against this. This custom is also cited by the Rema (Shulchan Orech OC167.5) who adds that the table is akin to the altar and food to the korban and that we are told (Vayikra 2:13) to add salt to all our korbanos.