You're probably thinking of this quote from Cinefex #65, p80):
Among the largest of them was the *Millenium Falcon*—whose redesign by Joe Johnston was purportedly inspired by Lucas’ idea of a hamburger in space. “The original concept called for the *Falcon* to sail like a giant sunfish,” explained Lorne Peterson. “It would lift off on its horizontal axis, then rotate into a vertical configuration and fly opened on edge with the front mandibles pointed forward. We never actually shot it that way, though, because George decided he liked the look of it flying horizontally.
I have a pet theory that it was inspired by a John Berkey painting. But still, from that idea, to the final McQuarrie drawing? A huge hole...