To begin with, I keep on getting different directions depending upon the person (in terms of whether it's low, or medium, or medium low). My mom says you should simmer pho broth on LOW heat, but based on some descriptions of "simmering", it seems like it would be a higher temperature, since simmering is apparently the point before boiling. On the other hand..if you go too high (even medium high) it would just end up boiling over time...So is low fine?
Also, I know there's a temperature range where it's safe for food to be in without the risk of bacteria multiplying. Would simmering on low overnight be in that range or is it risky? :o