Shailah of the Week by Rabbi Zvi Nussbaum
Rabbinic Coordinator, Kosher Hotline Administrator for the Orthodox Union
Shulchan Aruch (Orach Chaim 608:4) writes that on erev Yom Kippur, one should eat light foods that are easily digestible, so one will be able to daven on Yom Kippur with proper concentration.
There is a common custom to dip challah in honey.
Mishnah Berurah (608:16-18) writes that one should not overeat.
It is proper to serve chicken, but red meat, and especially fatty meat, should be avoided.
Wine and other intoxicating beverages should not be served.
One should avoid foods that are overly spicy or vinegary.
Sesame should be avoided, since it can cause reflux.
Based on the Tur (Orach Chaim 604), some have a minhag to eat fish on erev Yom Kippur. However Kitzur Shulchan Aruch (131:12) writes that it should not be served at the seuda ha’mafseket, but rather should be eaten earlier in the day.