My Step Daughter Who Is 10 Years Old Has Very

My step daughter who is 10 years old has very rigid food choices. Only eats foods that start with the letter P. Peaches, pizza, peanut butter, pancakes.... It makes it very difficult at dinner time and usually ends in emotional out breaks. We handle this very calmly but she just freaks out if we ask her to just try a bite. I don't know what to do. I hate dinner time.