1. Cooking a liver

Tannaim disagree about the halachah of cooking a liver: Rebbe Eliezer says אוסרת ואינה נאסרת – it prohibits other foods cooked with it, but does not itselfbecome prohibited, מפני שפולטת ואינה בולעת – because it continuously discharges blood and does not absorb any while being cooked. [The liver’s blood only becomes forbidden after leaving the liver.] Rebbe Yishmael the son of Rebbe Yochanan ben Berokah says that מתובלת – a seasoned [liver], and שלוקה – a stewed [liver], do become forbidden, because seasoning or extended cooking can cause the liver to reabsorb its forbidden blood. The Gemara relates that Rav Huna חלטי ליה בחלא – sealed [the blood inside the liver] by placing it in vinegar, and Rav Nachman חלטי ליה ברותחין – sealed it by scalding it in boiling water, to prevent blood from being emitted when it was later cooked with other food. Rava told Rav Pappa that the vinegar itself must also be permitted. Otherwise, if some blood seeps into it, the liver would be prohibited as well, because כי היכי דפליט הדר בלע – just as it emits blood into the vinegar, so it later absorbs it again (once the liver is no longer discharging blood).

1. Roasting a liver or udder above meat

The Gemara states: כבדא עילוי בשרא – if a liver was roasted on a spit above meat, the meat remains permitted, because דמא משרק שריק – the blood slides off and is not absorbed by the meat. If one roasted כחלא עילוי בשרא – an udder above meat, the meat is prohibited, because חלב סרוכי מסריך the milk clings to the meat and is absorbed by it. Rav Dimi of נהרדעא taught these cases the opposite way: כחל roasted above meat, does not prohibit it, because milk of a shechted animal is only prohibited מדרבנן; roasting a liver above meat does prohibit it, because blood which leaves the liver is prohibited מדאורייתא.

Mereimar announced the halachah: if either a liver or udder is roasted under meat, the meat remains permitted (since the blood or milk drips downwards). If either is roasted above the meat, the meat is permitted בדיעבד, but this should not be done לכחתלה.

1. נ"ט בר נ"ט

The Gemara discusses דגים שעלו בקערה – fish which were placed hot on a meat plate. Rav prohibits eating the fish together with כותח (a dairy dip), because the fish absorbed meat flavor from the plate. Shmuel permits eating it with כותח, because נותן טעם בר נ"ט הוא – it is only an imparted taste of an imparted taste. The fish only absorbed flavor from the plate, which itself had only absorbed flavor from meat. Meat flavor so far removed from its original source is not the equivalent of meat. [Had the fish been cooked together with meat, it would be prohibited to eat with כותח. Or, if hot milk would have been placed into a meat dish, it would be prohibited.] Rebbe Elazar was once standing before Shmuel when Shmuel was served fish which had been placed hot on a meat plate. Shmuel ate it with כותח, and offered it to Rebbe Elazar, who did not eat it. Shmuel said: לרבך יהיבי ליה ואכל ואת לא אכלת – “I gave such a dish to your teacher (Rav) and he ate it, yet you do not eat it? Rebbe Elazar later asked Rav if he had retracted his stringent view. Rav replied: חס ליה לזרעיה דאבא בר אבא דליספי לי מידי ולא סבירא לי – “Far be it from the child of Abba bar Abba (i.e., Shmuel) to serve me something which I do not hold is permitted!” The halachah follows Shmuel.