We may not roast the pesach-offering either on a [metal] spit or on a roasting tray.  R' Tzadok said: It once happened that Rabban Gamliel said to Tavi, his slave, “Go out and roast for us the pesach-offering on the roasting tray.”  [If] it touched the earthenware of the oven, he must pare off its place. [If] some of its juice dripped onto the earthenware and dripped back onto it, he must remove its place. If some of its juice dripped on the flour, he must remove a handful from its place.