The Foundation Stone Haggadah: Matzah 2
Apparently, eating Chametz is very dangerous and it makes sense not to eat it. So why do we eat an offering on Shavuot that is made almost exclusively of Chametz? In the words of the Zohar, if we are not allowed to eat Chametz and Machmetzet on Pesach, why do we eat Chametz on Shavuot when we are supposed to be at our highest level? Moreover, this is the only time when we have an offering made of Chametz. Says the Zohar, this doesn’t make sense. On Shavuot, the Torah was given, and the Yetzer Hara was destroyed. So why would we eat Chametz then on this day?
The Zohar relates a parable about a king who had an only son who became very ill, and could not eat. But one day he was hungry and the doctor said he should eat food that contained medicine. The doctor cautioned that when he will eat this medicated food there shouldn’t be any other food in the house. Thereafter, the king’s son was able to eat any kind of food. Similarly, when the Jews left Egypt, they didn’t have any idea about the secrets of things. They were ‘ill.’ So God decreed that they should eat medicated food, the matza, without eating any other kind of food. With the matza, they came to understand the deeper secrets. After Pesach, Chametz cannot do any damage. And when you eat matza you have to have in mind that this is a medicine for faith in God so as not to be taken in by the Evil Inclination.
The Shalah (Shenei Luchot Habrit) goes into a little more detail on this. There’s a Gemara in tractate Kiddushin that’s says that the matzot that the Jews took with them out of Egypt tasted just like the Manna.