Q. If a Jewish individual lighted a fire, and then the Gentile put the pot (with meat) on the fire. The food had NOT yet cooked one third, when the Jew turned off the fire. Then the Gentile turned the fire on and completely cooked the meat, is the meat prohibited because of Bishul Akum*?
A. Horav Shlomo miller's Shlit'a opinion is that it is permitted, if the meat did not get cold yet (50º C or at least 45º C, not lower). It would be then considered still being cooked by the original Yisroel.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit'a
*A Rabbinic prohibition of eating certain foods when cooked by Gentiles. It is part of a set of decrees instituted to prevent intermarriage and assimilation.