Eating out can be very difficult when it comes to managing soy allergies. Most restaurants cook with a blend of vegetable oil. More often than not, they contain soy. You’re best bet is to find restaurants that do not use a blend.
Authentic Mexican restaurants typically use corn oil. Their flour tortillas are often made from water and flour. My favorite Mexican restaurant in Chicago is El Tapatio, located on the corner of Ashland and Roscoe in Lakeview. It’s safe to eat, the staff is extremely friendly, and you can’t beat their margaritas! http://www.cafeeltapatio.com/ I suggest checking it out!
Authentic Italian restaurants are also typically a safe bet. Most of them use pure extra virgin olive oil. Quartino Ristorante & Wine Bar at State and Ontario has always been very accommodating. I love their bolognese sauce! http://www.quartinochicago.com/
Chop houses also tend to be very accommodating, and the chefs always seem to know what to look for. Keefer’s at State and Dearborn is a great one! Not only are they extremely helpful and knowledgeable, our server asked me to name a few appetizers and entrees I was interested in, and checked on each of them! http://www.keefersrestaurant.com/index.html
I always suggest calling ahead and asking them to check their cooking oil. It’s not uncommon that restaurants have the misconception that “soy” refers solely to soy sauce. Don’t be afraid to be specific!