In general, lima beans cook pretty fast and require no soaking. Sometimes, however, dried limas have been sitting on the shelf for so long that they never become tender when cooked. If you know that your lima beans are more than 1 year old, soak them to be safe before cooking. Fresh lima beans can be shell very quickly. Just cut a thin strip from the inner edge of the pod with scissors. The beans will fall out as the pod opens.
To avoid tough lima beans, hold off on adding acidic ingredients, such as tomatoes, vinegar, or wine, until after the lime beans have cooked through. Acids react with the starch in beans and prevent them from swelling.
** Asian Recipes