Hi, a have a question in hilchos derech eretz by a seudah. May I bite into a sandwich or pizza ? does it make a difference if the bite is less than a kzayis? thank you
Yes, you may bite in to such foods as is the common custom.
Sefer Vzos Habracha pg. 15 quotes many contemporary poskim that since this has become a societal norm there is no violation of derech eretz as per Shulchan Aruch O:C 170.