Customs of Shabbat HaGadol
The Minhag Yisroel Torah brings two interesting minhagin regarding special food to eat on Shabbos HaGadol. The first is a minhag from Frankfurt where the people would save a piece of the afikoman each of the nights of Pesach and hold it by them the entire year. On Shabbos HaGadol they would put the afikoman into one of the Shabbos foods and eat it.
Another minhag was to save a food from the Mishloach Manos received on Purim and eat it on Shabbos HaGadol. They would eat a little bit of the Mishloach Manos each day from Purim until Shabbos HaGadol, when they would finish the last remnants. The reason for this is because the kedusha of Pesach start thirty days before Pesach which is the day of Purim. We want to connect the kedusha of the two Yomim Tovim of Geula together.