Start by rinsing the dried green split peas under cold water until the water runs clear; set aside.
Chop the onion, carrots, and celery into roughly 1-inch pieces—no need to be perfect; this rough chopped look adds to the rustic charm.
Add all the ingredients—rinsed peas, chopped vegetables, broth, bay leaf, thyme, pepper, and smoked ham—to the slow cooker, stirring everything together to combine.
Cover the slow cooker and cook on low for 6 to 8 hours, or on high for 3 to 4 hours. During cooking, you'll smell the aromatic vegetables and smoky ham filling your kitchen with cozy scents.
Once the peas are tender and have mostly broken down, remove the bay leaf and ham hock (if used), then shred the ham and stir it back into the soup for added flavor.
Use a wooden spoon to mash some of the peas directly in the pot, creating a thicker, velvety texture. Taste the soup and adjust with salt, pepper, and a splash of apple cider vinegar for brightness.
Let the soup sit uncovered for about 10 minutes to allow flavors to meld and the texture to thicken slightly, then give it a final stir.
Scoop the soup into bowls, garnish with fresh herbs if desired, and serve hot with crusty bread for a cozy, nourishing meal.
