In a large colander, rinse peas and pick out any stones or twigs as well as any peas that are discolored or wrinkled. Put peas in a large soup pot that has a lid; add enough water to cover peas by about 2 inches. Cover pot with lid and soak peas overnight. Drain off water and add 6-8 cups of fresh water. Add the bacon fat, smoked ham hock or smoked turkey leg and diced onion. Turn heat to medium; bring peas to a boil and then reduce heat to medium-low and simmer peas for 1-2 hours or until they are tender. Note: black-eyed peas cook faster than other beans, so you should start checking them for doneness after one hour. When peas are done, meat from ham hock can be pulled off hock and added to beans if desired. Use peas in Hoppinâ John or freeze for later use.