Terumot, Chapter Ten, Mishnah Eleven
1) Rabbi Yose says: Anything stewed with [terumah] beets becomes forbidden, because they impart a flavor.
2) Rabbi Shimon says: cabbage from a field artificially irrigated [that is stewed] with [terumah] cabbage from a field watered by rain, is forbidden because it absorbs.
3) Rabbi Akiba says: all things cooked together are permitted, except those with meat.
4) Rabbi Yohanan ben Nuri says: liver renders other things forbidden, but does not become forbidden, because it gives off [flavor] but does not absorb.
Section one: Stewing refers to cooking vegetables or meat until they are very soft. Rabbi Yose says that hullin vegetables stewed together with terumah vegetables remain permitted, with the exception of terumah beets which do impart a flavor to that which they are stewed with.
Section two: According to Rabbi Shimon, cabbage that grows in a field that is artificially irrigated is more susceptible to outside flavor than cabbage grown in a field watered by rain. Hence, if the latter is terumah cabbage and it is stewed with the former, all of the cabbage must be treated like terumah.
Section three: Rabbi Akiba says that anything cooked (not stewed) together is permitted, except for forbidden meat. If, for instance, pork was placed in a pot of beef, the beef would absorb the taste of the pork and it would become prohibited.
Section four: Rabbi Yohanan ben Nuri says that liver gives off flavor and therefore if it is cooked with other meat it renders it prohibited, but it itself does not absorb flavor. Hence if the liver is permitted and the other meat is prohibited, the liver remains permitted. This is because the taste of liver is very strong (never developed a taste for it myself).