1. In a large pot, heat a bit of oil over medium heat. Add the chopped onion and minced garlic, and cook until softened.
2. Add the diced ham and cook for another 2-3 minutes.
3. Stir in the lentils, carrots, and celery. Pour in the chicken broth and water.
4. Add the dried thyme, salt, and black pepper. Bring to a boil, then reduce the heat and let it simmer for about 45 minutes, or until the lentils are tender.
5. Adjust seasoning to taste and serve hot.
Notes:
This stew is even better the next day, so consider making it ahead of time.