"Ever wondered what to do with the leftover bone from that spiral ham (or regular ham) from the holidays? Well, with this soup you can make one last great meal from it without spending a lot of money!"
Place lima beans in a large bowl and cover with several inches of water; soak 8 hours to overnight.
Bring water, ham bone, and onion to a boil in a pot. Reduce heat, cover, and simmer until onion is tender, about 1 hour.
Drain and rinse lima beans and add to the pot with the ham bone. Add brown sugar, Worcestershire sauce, hot sauce, dry mustard, and salt. Simmer, covered, about 2 hours. Uncover and continue simmering soup until beans are tender, about 30 minutes more.
Remove ham bone from soup; cut the meat into bite-sized pieces. Discard bone and return meat to the soup.