Matzo ball soup.
Day One, no leavened foods, check.
We had some leftover matzo balls --like buttah!--and chicken from my mom's soup last night, but we ran out of broth. No problem, because I had chicken carcasses! Tasty, tasty chicken carcasses left from the roast chickens I served last night. I boiled them with sad baby carrots from the bottom of the vegetable crisper and the wilted parsley from the seder plate and some pathetic old onion I found in the fridge, et voila, more broth!
It actually tasted really good. Even better, I consider this dinner basically free. Because I made it out of garbage.