What to do in a restaurant. This was SO HARD for me at first. I was so apologetic. For what it's worth, we are typically ok with fried (tree nut allergy - peanut is ok) and 100% avoid desserts unless they can show me the ice cream carton, open a new one, and sterilize a scoop.
How to call a restaurant - what to ask to determine safety for food allergies. I do this SO OFTEN. You can usually get a feeling pretty fast about their ability to handle allergies! If they start trying to figure out how to handle you, run. If they can rattle off their typical procedures, you're good!