Sweet and Sour Green Beans

We have a banquet hall at a Knights of Columbus hall nearby. I go there several times a year for different functions and each time I go I hope that these are on the menu. These sweet and sour green beans are the bomb! I love them! I'm going to have to try to duplicate them at home. Anyone ever made these who can steer me the right direction? If so, leave me a comment. I'm thinking some vinegar, sugar, onion and bacon. I'll have to experiment!