So I am looking for a little insight on sweating. I will use cream soups as a example. So in school when we would make cream soups the instructor always told me to sweat (with a lid on the pot) the onions till translucent then add the other veges (garlic sometimes, carrot, cuc, etc).. The instructor was very clear that he didn't want the onions caramelized and to only sweat the other mirepoix and not to develop color. Well recently I worked at a resort and the head chef there wanted me to caramelize the onions and the garlic while making cream of mushroom soup. I want to know why my teacher was very strict about not doing it and this chef was pro doing it. I figure it has something to do with color and if im looking to develop a sweeter taste in the soup that the caramelized onions and garlic will give the dish a sweeter flavor. Any insight would be greatly appreciated and also why when I sweated onions till translucent at school did the chef always say to put a lid on the pot?
PS: I am away from school doing a internship so I can't ask my instructor.