This is a more literal translation - deviating slightly from the English idiom "to stew in one's own juice" - it depends really if you want the more literal translation or not. I still think that using "cauldron" is understandable in English. Incidentally the idiom вариться в собственном соку was not used here, which leads me to believe that the original specifically wanted to use the word "cauldron" (котел) - perhaps a pejorative subtext within the original??