From: Rabbi Moshe Sofer
To: Rabbi Mordechai Leib
The Chasam Sofer rules leniently that one may sell to a non-Jew a vessel whose walls have absorbed the flavor of basar bechalav, even on the same day as the prohibited cooking. The non-Jew pays nothing extra for the absorbed taste, which is degraded upon first extraction; there is a double doubt regarding any prohibited benefit; and the concept of rotzeh bekiyumo does not apply to basar bechalav, since unlike chametz or avodah zarah there is no Torah obligation to destroy it.
Source: Shu"t Chasam Sofer YD §98