With a sulphite allergy, it is nearly impossible to avoid them at all anyways; never mind cross contamination. And it is too complicated to explain to restaurant staff, so I don't bother to worry them except maybe to avoid certain ingredients like mushrooms, wine or coconut. I have gotten to the point where I feel comfortable eating at the few local restaurants we have here. As I have had to cook everything from scratch, I know basically which ingredients could be in each dish, so I make careful decisions. For example, I avoid guacamole because it could have bottled lemon juice in it, I do not eat seafood in restaurants, or if I think something might have wine in the sauce. I always make sure that I have my Epipens with me, I try to have another adult with me, and I tell someone as soon as I think I may be experiencing a reaction.
The simple answer is we don't eat out. Its too risk given my little one's severe allergy to dairy. Most people do not understand that microscopic amounts of an allergen can cause a reaction. We've found a few vegan restaurants that we trust and bakeries that cater to the allergy community that are fantastic.
I found one restaurant in Atlanta area that was awesome. Papadeux (sp?). They even say on the menu if you have a food allergy contact your server. Then they bring s lady out who is dietician she goes thru the menu to let you know what you can eat and goes back to the kitchen to make sure it's cooked right. Never felt so safe eating out
I'm limited to restaurants I can frequent so I have found those who cook from "scratch" and give them my business. It's wonderful to go to those places.
I avoid cross contamination by always viewing the menu online and then calling ahead and going over my allergies with a maager. Upon arrival to the restaurant or outing, I ask to talk to the manager and give them my chef card with my allergies (https://www.foodallergy.org/file/chef-card-temp...) This has gone over very well, because they can take the card to the kitchen and cross reference everything.