From: Rabbi Moshe Sofer
To: Rabbi Aryeh Leib Stampeh Segal
The correspondent challenges the Beis Yosef's reading of Rashi that an uncovered oven is equivalent to meat on open coals. The Chasam Sofer rejects this, explaining that a tanur is open on top and requires a separate cover, aligning with the Beis Yosef and Tosfos.
Source: Shu"t Chasam Sofer OC §77