My workplace does soup day every Tuesday, where 2 people each make a pot of soup to serve about 20. Last time I made a chicken pozole, which went over very well, but was a lot of work with all the toppings etc.
I need something that can be made ahead and kept warm in a slow cooker, as some people eat at first recess and some at second. Also, teachers tend to only get 15-20 minutes to eat!
There are no vegetarians, but no shellfish or nuts due to allergies.
What are your tried and true soup recipes?