In brief
Smooth, crispy pods are a good base for garnish. Cooking ends at the desired texture, not just at the expiration of indicative minutes.
Useful to know
In green beans, it looks for smooth, brittle and crunchy pods. The University of Iowa recommends avoiding brown spots and a moist, sticky surface. The product is refrigerated in an envelope. [1]
Before cooking, rinse well under running water and separate the ends. The manual offers boiling, baking, or cooking in an appropriate microwave pot, with all three methods checking the resulting texture. [1]
For a sample garnish, select close-sized pods and use one method. If you mix completely different sizes, check more than one pod before you decide that the whole batch is ready.
Do not carry this preparation over to the dry ripe beans: there the product, the weather and the technology are different. The word "beans" in a recipe title should be read along with the description of whether fresh pods, dry grains, or finished canned product are used.
Sources
For further detail and to check the information: