How to Keep Lettuce Crisp.
Lettuce can be kept crisp and fresh for several days, if necessary, by placing the roots in water. Do not let the water come up as high as the leaves. When ready to serve the lettuce, wash it leaf by leaf in a pan of cold water, and drop it into another pan of ice-water. It will become crisp in a few minutes. Shake the water from the leaves before serving.