Why did Hashem command us to eat specific foods at the Pesach seder?
The specific foods we eat at the Seder are not a mere ritual. They are a vessel to connect us to particular channels of Divine flow, which are available only at that time.
As we are human, dwelling in the earthly/material realm, we are able to tap into these Divine flows solely through the performance of mitzvot – i.e., an action which combines materially (Lower World) with spirituality (Higher Worlds) – accordingly to the will of Hashem.
“Pesach enables us to undergo a personal exodus from Egypt by transcending our individual limits. Accordingly, G-d gave us the mitzvah of eating matzah to help us internalize that experience. For our food is assimilated into our bodies, becoming part of our flesh and blood. Eating matzah thus converts the experience of self-transcendence into an integral part of our beings.”