1. In a medium bowl or liquid measure, combine the water, bouillon cubes and spices and whisk to combine (it's ok if the bouillon cubes don't completely dissolve).
2. In a medium round slow cooker (about 4-quart), layer peas, barley, ham, carrots, onion and celery. Do not mix.
3. Pour in the water/spices mixture and add the bay leaf to the slow cooker.
4. DON'T STIR!
5. Cover the slow cooker and cook on high for four hours or on low eight hours, until the peas reach the desired creamy, soft texture.
6. Remove the bay leaf, stir well, and add salt and pepper to taste, if needed. Serve immediately.
7. Note: Upon sitting and/or refrigerating, this soup thickens considerably. Simply add water or chicken broth to thin the soup to the desired consistency before re-serving.