It has been discussed here previously regarding the Sous-vide method of cooking.
However I have a separate question. What type of method is halachically categorized as? Is it Tzli or is it Bishul?
Tzli is defined as cooking through exposure to an open fire. For simplicity sake we’ll call it barbecuing.
Bishul is defined as cooking through water. Like boiling noodles in water.
However regarding the Sous-vide cooking method, when it is placed in the vacuum sealed bag, and cooked in the pot of water. It is not being exposed to the water, rather to the consistent heat that the water is producing, and thus the food is being cooked. Perhaps that is Tzli, in that it is a dry heat. Or no, it is considered bishul because the cooking is being caused by a boiled water - or perhaps (depending on which food is being cooked) the food is being cooked by its own juices and fats.
The practical ramifications if whether we define it as Tzli or Bishul is being that the Sous-vide method does not “brown” the food, like a barbecued piece of meat (One limitation of sous-vide cooking is the fact that browning (Maillard reactions) happens at temperatures above the boiling point of water Wikipedia). The food comes out softer (also more juicer, which is why people use this method).
Let’s say someone wanted to add that browning to their piece of meat. And on Shabbos (the food was cooked entirely from before shabbos) places it on the plata (on an upside down pot that is Yad Soledes hot) to give the food the desired brown or crunchy texture.
The basis of this question is based on a different argument, if whether or not, despite the food being fully cooked and subject to אין בישול אחר בישול, but if you cook the food again using a different method, ie. Food was cooked through בישול and then cooked again using צלי - it would be assur. But if Sous-vide is considered Tzli it would be permitted Source
Thus what is Sous-vide considered? And would putting the food onto the plata to give it the crunchy burning affect be subject to אין בישול אחר צלי or vice versa? is the way its cooked also considered צלי קידר - cooking in its own juice, which is considered בישול?