What isthe best way to ladle soup on Friday night when the soup pot is on a hotplate (without temperature control)? Does the ladle become a kli rishon when putting it into the soup to serve it? Is it better to serve all the bowls at once?
Does it make a difference if the ladle is plastic or metal?
Please cite sources.
Because a liquid that has cooled is subject to the prohibition of bishul on Shabbos (it may not be reheated), a wet soup ladle that is left outside the pot and has cooled down may not be put back into the hot pot of soup.
Practically speaking if someone wants a second portion of soup, there would be a problem returning the ladle to the pot.
The solution is to either keep the ladle inside the pot and thus avoid the entire issue, as it will not cool down, or to dry it before returning it to the pot.
Concerning the general status of the ladle, the consensus is that if the ladle is the pot for a long time, it takes on the halachic characteristics of a kli rishon (Mishnah Berurah 318:87). Usually, we will treat the ladle as being a safek (possibly a kli rishon, but possible a kli sheini) – see Taz, Yoreh Deah 92:30, and see also Chazon Ish (Orach Chaim 122:3).