When we were slaves in Egypt, every single day of the week we ate only Matza. For breakfast, lunch and dinner! (ha lachma anyia di akhalu abahatana be-ar'a deMitzraim). Matza was the food conceived by the cruel Egyptians as the ideal meal for the Jewish slaves. It was cheaper than any other food, and lasted longer than regular bread in the slave's stomach. And it was very easy to prepare. To make regular bread you need to let the dough rest for approximately 10-15 minutes and only then you would place the spongy-dough into the oven. In Egyptian captivity, the raising of the dough was skipped. Instead, they had to put the flat dough into the oven. Why? Because the Jewish slaves had to work without a pause. The Egyptians were not willing to concede the Jewish slaves 10 extra minutes to rest, which would allow the dough to raise and made it into bread.
On the other hand, upon our sudden departure from Egypt, we also ate Matza. We did not leave Egypt emigrating from it by a slow progressive process. We were rescued by HaShem in a super speedy (bechipazon) operation that lasted just one night. (Can you visualize the mobilization of 3 million people, leaving all together in one night?). There was no time to prepare any normal food for the journey. For a different reason, there were no 10 extra minutes to wait for the dough to rise. In our memories, therefore, Matza has also the taste of "rushing into freedom".
Matza then symbolizes both, the flavor of freedom and the bitterness of slavery. During Pesach we literally relive the sourness of captivity and the sweetness of liberty, both represented by the Matza.
Matza celebrates our freedom, but without forgetting our suffering.
Martha Stewart visits a Matzah factory