As a general rule, you can cook them from raw to crisp tender in about 4 minutes. This is especially true in steaming and boiling. That said, there are several ways to cook green beans and cooking times will vary depending. Frying is faster and grilling or roasting is slower. Note: while you can use the same cooking technique to cook haricot vert (or French green beans) as you would regular green beans, they cook more quickly so adjust cooking times down when following recipes for regular green beans.