Is blowing on a frying pan unsanitary?
Incomplete common sense answer (no idea about local regulations. If this should have been a comment, somebody tell me! :) People breathe in kitchens while there are open pots, and blowing is a form of breathing. Food is not ever considered completely sterile unless pressure cooked/canned, cold sterilized (chemically or by pickling in extremely harsh pickling solutions), or irradiated. Also, unless things are served straight after that, they will be rather thoroughly cooked in the depicted scenario - if there are germs in that breath, they are cooked to death; spores will not matter much with food immediately served; if there was poison the cook would be dead or ill too. Virii could be a problem too,