From America's Test Kitchen
Most vegetable side dishes require last-minute preparation, but green beans are an ideal side dish that can be prepared largely beforehand without sacrificing texture or flavor. We wanted a foolproof way of cooking beans ahead of time and then simply reheating and seasoning them just before serving.
The easiest way to do this was to blanch the beans in salted water, shock them in ice water to stop the cooking process, and then towel-dry and refrigerate them until needed—a process that could be completed up to three days before serving. To serve, we reheated the beans in a skillet with a little water and flavored them with a butter sauce. The small amount of water came to a boil quickly and evaporated almost completely, helping to heat the beans in just a minute or two for a quick and flavorful side dish.
Serves 4 to 6
Tongs are the tool best suited to tossing the beans in the pan and arranging them on the platter. To blanch, dress, and serve the beans without holding them first in the refrigerator, increase the blanching time to 5 to 6 minutes and don’t bother shocking them in ice water. Instead, quickly arrange the warm beans on a serving platter and top with the sauce you’ve prepared as the beans blanch.