Rinse the lentils thoroughly under cold water and set aside.
Prepare the vegetables by dicing the onion, carrots, and celery.
In the slow cooker, combine the rinsed lentils, diced vegetables, minced garlic, and diced ham.
Add the broth, bay leaf, dried thyme, salt, and pepper.
Stir well to combine all ingredients thoroughly.
Cover the slow cooker and set it on low for 6-8 hours or high for 3-4 hours.
Once cooked, remove the bay leaf and adjust seasoning if necessary.
Serve hot, garnished with fresh herbs if desired.