It is available as a dry bean and as a green bean(usually as frozen). Generally, the grocery stores used to carry dry beans in their International aisle and the green bean in the frozen vegetable aisle. Lima bean is also called butter bean in Europe and double bean in India. Both of these are equally good. However, the frozen green bean is more comfortable as you can use it straight away from your freezer. On the other hand, you need to soak the dry bean overnight and precook it before adding it to the curry. The one advantage of using dry beans is storing unused beans for a couple of years.