To make pea-soup in a Crock-pot, add green split peas into the slow cooker, along with chopped onions, carrots, celery, onions, seasonings and optional ham. Add several cups of water, depending on the size of your slow cooker, and cook on low for eight to 10 hours.
Start with freshly rinsed dried green split peas for Crock-Pot split pea soup, as the slow cooking time allows the dried peas to fully reconstitute. For a 4- to 5-quart Crock-Pot, add a 16-ounce packet of split peas to the cooker insert. Add about a 1/2 to 1 cup of carrots, celery and onions on top of the peas. You can add more or less of any vegetable, depending on your preference. You can also add optional aromatics, such as garlic cloves, bay leaves, thyme sprigs and leeks.
A meaty ham bone is traditional in split pea soup for more flavor, but is not a requirement. You can also use 2 cups of diced cubed ham or a smoked turkey leg.
Whether you include meat or not, add about 7 cups of water or chicken broth to the Crock-Pot after adding all the ingredients. Cover and cook the soup on low. If you use meat, remove it from the cooker and pull the meat from the bones. Stir the meat back into the soup before serving.