Gemara

(Mishnah): If any skin was tanned or trampled enough for tanning, it is Tahor, except for human skin.

Chulin 97b (Rav Acha): Shmuel taught that salted food is like Rose'ach (boiling hot), and pickling is like cooking;

Inference: Salting is not like cooking. Rather, it is like roasting.

113a (Shmuel): Blood leaves the meat only if it is salted very well and rinsed very well.

Rishonim

Rif (Chulin 42b): One must leave meat in salt the time to slaughter and flay the animal, and check the meat from Chelev and all Isurim. (If it was salted) less than this amount of time, it is forbidden.

Rambam (Hilchos Ma'achalos Asuros 6:10): One leaves meat in its salt the time to walk one Mil. Afterwards he rinses it very well until the water leaves clear. He immediately casts it into boiling water, but not into lukewarm water, so it will whiten immediately and blood will not exude.

Rebuttal (Ra'avad): I never heard or saw this. Any redness that leaves after salting is merely Yayin (i.e. juice - PF) of the meat. Anyone who is more stringent than this must bring a proof.

Magid Mishneh: The Rambam says that one leaves meat in its salt the time to walk one Mil. Bahag says that the Shi'ur for salting is like the Shi'ur for roasting. A support for the Rambam is the Shi'ur for tanning leather, which is the time to walk one Mil (Shabbos 75b). Some obligate one who salts meat on Shabbos, for tanning. Even though we hold that tanning does not apply to food, we may learn that salting is tanning. Since Chachamim did not specify the Shi'ur, presumably it is the Shi'ur for tanning. I later found that the Ramban brings from Ge'onim that the Shi'ur for roasting is the time to walk one Mil.

Rosh (Chulin 8:38): A case occurred in which meat was salted and delayed the time for roasting, and it was put in a Kli without rinsing. The Kli became full of brine. Rashi permitted it. Brine is not blood. It is merely juice of meat and its moisture. After the time for roasting, we rinse it and cook it in a pot, without concern for brine it emits.

Hagahos Ashri (43): We leave meat in salt the Shi'ur of time to roast the piece itself, based on its thickness and size.

Mordechai (Chulin 730): Bahag says that the Shi'ur for salting is like for roasting. Avi ha'Ezri disagrees, for if so, the law is not uniform. A big fire roasts more quickly than a small fire! I saw in the name of Rashi that the time for salting is a Mil. Or Zaru'a says that it is the time to roast the piece itself.

Terumas ha'Deshen (167): People say that one should leave the meat in salt for an hour. We do not require a proof or support for this Shi'ur. People conduct like Or Zaru'a and Sha'arei Dura, who wrote that the Shi'ur for salting is like for roasting that very piece, based on its size and thickness. Since there is not one Shi'ur for all pieces, people fixed a Shi'ur of one hour. We find that the Shi'ur of an hour was adopted without reason, e.g. in order to gather wood (to burn Chametz - Pesachim 12b). Even though some gather in a quarter hour and some need more than an hour, Chachamim fixed a clear Shi'ur. We can say similarly here. In any case, there is a support from Pesachim 58a. When Erev Pesach is on Erev Shabbos, we must roast the Pesach before Shabbos, so we slaughter the afternoon Tamid at six hours, an hour and a half earlier than normal, to allow time to roast the Pesach.

Note: Presumably, the text of Terumas ha'Deshen should say 'we slaughter the Tamid at six and a half hours (like it says explicitly in Pesachim), an hour earlier than normal. The next words of the Terumas ha'Deshen (below) support this. To derive that it takes one hour to roast the Pesach, he must assume that when Erev Pesach is not Erev Shabbos, people in the last group (to slaughter it) arrive home and have time to put it to roast at the very end of the day. He also assumes that a big ox roasts in the time needed for a whole yearling kid or lamb.

Terumas ha'Deshen: This shows that even a whole animal roasts in one hour. Therefore, people hold that there is no piece so big and thick that one hour does not suffice to roast it. However, in pressed circumstances, e.g. to honor Shabbos or guests, one may rely on the Rambam, who says that the Shi'ur is the time to walk one Mil, i.e. 18 minutes. I proved this from the distance that a man can walk in one day, i.e. 40 Mil in 12 hours (Pesachim 93b).

Kaf ha'Chayim (YD 69:89): Some say that the time to walk one Mil is two fifths of an hour (24 minutes).

Note: The Terumas ha'Deshen explains that one walks 40 Mil in 12 hours (720 minutes), so one Mil is 18 minutes. The Rambam himself (Perush ha'Mishnayos Pesachim 3:2) says that the Shi'ur is two fifths of an hour. Perhaps he holds that the 'day' for walking is from dawn until Tzeis ha'Kochavim, i.e. 16 hours, so it is a third more than the Terumas ha'Deshen's calculation.

Rashi (55a DH she'Avdan): It says in Berachos and Pesachim that the Shi'ur of tanning is the time to walk one Mil.

Tosfos (Chulin 112 DH Hani): Bahag says that the Shi'ur for salting is like for roasting, since salting is like roasting.

Poskim

Shulchan Aruch (YD 69:6): Meat must be left in salt at least the time to walk one Mil, which is about a third of an hour.

Beis Yosef (DH v'Shi'ur): The Rosh, Tur, Tosfos, Bahag and Rashba say that the Shi'ur for salting is like for roasting. This is because blood exudes through salting like through roasting. The Magid Mishneh brought from the Ramban that the time to walk one Mil suffices. This connotes this is enough even for a whole ox. Even a small piece requires the time to walk one Mil. Chachamim did not distinguish. However, Hagahos Ashri says that we leave meat in salt the Shi'ur of time to roast the piece itself, based on its size and thickness. The Rif requires the time to slaughter, flay, and check from Isurim. The Rosh did not bring this in his Pesakim.

Beis Yosef (DH Kasuv, citing Hagahos Sha'arei Dura 15:4): A case occurred in which legs of a lamb were rinsed and salted, but they did not delay (in the salt), and they were immediately put into a pot. It seems that it is forbidden. However, Shmuel taught that the meat must be salted and rinsed very well. He did not mention delaying in the salt. Also, charring extracts the blood through (roasting of) the fire. Also, if you consider the charring with the salt and there is the Shi'ur of delay, it is permitted.

Rebuttal (Beis Yosef): This Heter is wrong.

Gra (27): In Shabbos, we say that salting is liable for tanning. The Shi'ur for tanning is the time to walk one Mil. The Acharonim discuss this. Even though Bahag and the Ge'onim say that the Shi'ur for salting is like for roasting, based on Chulin 97b, the Magid Mishneh says that the Shi'ur for roasting is the time to walk one Mil.

Rema: One may rely on this b'Di'eved, or even l'Chatchilah in order to honor guests or for the needs of Shabbos, but if not, the custom is to leave it in salt for an hour. One should not deviate.

Shach (26): One may rely on this b'Di'eved if it was rinsed after delaying the time to walk one Mil (in salt), and was cooked.

Dagul me'Revavah: Isur v'Heter and Darchei Moshe permit b'Di'eved if it was rinsed after delaying the time to walk one Mil. They did not mention that it was cooked. The Shach added this, for if it was not cooked, why is this b'Di'eved? One can salt it again! This is no proof. Since it was rinsed, one would need to use more salt to salt it again. It is considered b'Di'eved due to the loss of salt. I say that the Shach is stringent only if it delayed only the time to walk one Mil. If it delayed close to an hour, e.g. three quarters of an hour, one need not salt it again. The stringent opinion holds that an hour surely suffices, We learn from Korban Pesach, which is roasted whole. Chachamim made a uniform Shi'ur of an hour even for a small piece. I say that if it delayed more than half an hour, one may be lenient after it was rinsed.

Pischei Teshuvah (13): Soles l'Minchah (15) cites Toras Asham, who says that 'honor of guests' refers to Chachamim or people of great reputation and deeds, or an Oni descended from a prestigious family, or Ashirim worthy of honor. It does not refer to people who beg for food. That is Tzedakah. Also, 'guests' means that they lodged in his house, but not that he merely invited them for a meal. Soles l'Minchah disagreed. He concluded that l'Chatchilah one should not invite a guest if he will need to be lenient about rinsing or salting, but if he already invited guests, he may be lenient (because Kavod ha'Briyos is great - Kaf ha'Chayim 94).

Kaf ha'Chayim (91): If one is unsure whether it delayed long enough, it is permitted due to a Sefek-Sefeka. Perhaps it delayed long enough, and even if it did not, perhaps the Halachah follows the Ra'avad and those who gauge based on the amount of blood that leaves. Aruch ha'Shulchan says that one should not be lenient about an Isur Torah, but most forbid cooked blood only mid'Rabanan. Even if Vadai it did not delay the Shi'ur, surely some blood left, therefore we rely on the Ra'avad.

Kaf ha'Chayim (92): If it did not delay and it was put in boiling water, we permit b'Di'eved if needed to avoid a big loss, because this is Chalitah. (It causes the blood to remain in the meat.)

Kaf ha'Chayim (95): It is considered pressed circumstances also if he is on the road and those he travels with will not wait for him, or a Choleh who wants to eat soon.

Kaf ha'Chayim (96): This refers to 60 minutes, at any time of the year.