Based on the above, the HeGyonei HaParsha (Vayikra pg. 49) wants to explain the minhag of dipping challah into honey on the night of Rosh Hashanah. The Gemara in Rosh Hashanah (16a) teaches: Rav Yehudah said: For what reason does the Torah say to bring shtei halechem [two loaves] on Shavuos? Because Shavuos is the time for the fruits of the tree. Therefore, Hakadosh Boruch Hu says: Bring in front of Me two loaves on Shavuos, so that the fruits of the tree will be blessed for you.
The Ritva asks: What does two loaves of bread which is a type of grain have to do with fruit of the tree? And he answers: We can say that we are going like the opinion (Sanhedrin 70b) that learns that wheat is a type of tree, and they learn that the Eitz HaDaas that Adam HaRishon ate from was wheat.”
According to this, since the sin of Adam and Chavah was done through the consumption of wheat, we dip challah (which is made of wheat) into honey to act as a tikkun [rectification] for the sin of Adam and Chavah, and to show that through teshuvah out of love, even the greatest of sins can be turned into mitzvos and into merits. And we can even add, that the sin of Adam and Chavah was on Rosh Hashanah, which makes it the perfect day for this.
