Inspect the dried beans carefully, removing any debris, stones, or broken beans. Rinse the beans thoroughly under cool running water using a colander. (Rinsing is essential, though soaking is usually not required for slow cooker cooking.)

Optional Flavor Boost: If you choose to maximize flavor, heat the tablespoon of olive oil in a large skillet over medium heat. Add the chopped onion, carrots, and celery. Sauté for about 5 to 7 minutes until the vegetables begin to soften. Stir in the minced garlic during the last minute of cooking until fragrant. If skipping, simply use raw vegetables.

Place the cleaned and rinsed dried beans directly into the basin of a large 6-quart or 7-quart slow cooker.

Add the sautéed aromatic vegetables (onion, carrot, celery, and garlic), or simply add the raw chopped vegetables if you skipped the sautéing step.

Nestle the large smoked ham bone into the center of the beans and vegetables. Pour in the 6 cups of chicken or vegetable broth and the 2 cups of water. Ensure all ingredients are submerged; if not, add a little more water until everything is covered by liquid.

Add the seasonings: the two bay leaves, dried thyme, dried parsley, and black pepper. Do not add additional salt at this stage.

Cover the slow cooker tightly with the lid. Cook the soup on the LOW setting for 8 to 10 hours, or on the HIGH setting for 4 to 5 hours, or until the beans are completely tender and soft.

Once the cooking time is complete and the beans are tender, carefully remove the ham bone from the slow cooker using tongs. Place the bone on a cutting board to cool slightly. Discard the bay leaves.

Allow the ham bone to cool for a few minutes. Pick any remaining meat from the bone, shred it or chop it into bite-sized pieces, and return the cooked ham meat to the slow cooker. Discard the remaining bone and any fat or gristle.

Adjust Consistency: If you prefer a thicker soup, you can smash about 1 cup of the cooked beans against the side of the pot with the back of a spoon, or briefly use an immersion blender to blend a small portion of the soup. Stir well.

Taste the soup and adjust seasonings. Because the ham bone can vary greatly in saltiness, this is the time to add salt, if necessary. Add the 1 tablespoon of apple cider vinegar or lemon juice to brighten the flavor.

Stir the finished soup well and let it sit covered on the WARM setting for 15 minutes before serving to allow the final flavors to meld. Serve hot.