You can cook frozen green beans in the same way that you cook fresh, and you don't even need to defrost them. If the green beans are packaged, just sauté and then steam them just as directed in this recipe. The same is true if you froze your own green beans. If the green beans were blanched before freezing, they will take about the same time as fresh green beans. If not, you may need to add a few more minutes of steaming to allow them to become tender.