My mom could cook one thing. Fried chicken. And my sister, who in all honestly turned out to be a great cook, made a mean potato salad. Not the type I'm prone to make - she couldn't readily get her hands on purple potatoes - but pretty darn respectable. These were the only things I thought one might consider proper picnic food. Then I moved to California.I'm a long way from the church picnics held in the basement of the Federated Church in Green Lake. Coleslaw rarely appears on the local picnic scene. I haven't seen a casserole line-up in …