Sort and rinse lentils. Soak overnight or at least 30 minutes beforehand.
In med. saucepan, heat oil. Stir in ham or sausage, onion, celery, and garlic, until tender.
Add lentils, bouillon cube, water, and salt and pepper. Bring to a boil.
Reduce heat, cover, and let simmer about an hour, until lentils are tender and soup thickens. Add more hot water if needed.