1. Preheat the oven to 275° F
2. Heat the oil in a large, heavy Dutch oven over medium high heat. Generously salt and pepper the ribs and place them in the pot to brown on all sides.
3. Remove the ribs to a plate and cover loosely with foil.
4. Add the onion, celery, carrots, rutabaga, and garlic and saute until the onion is becoming translucent, about 3 to 4 minutes.
5. Add the ribs along with the thyme back to the pot and cover with water until the water comes about half way up on the ribs.
6. Bring to a simmer, cover and place in the oven. Cook for about 1 1/2 hours until the meat is tender but not falling off the bones. I prefer the meat to be whole and able to be sliced without falling apart. That is to say not shredding off the bone when you pull it with a fork. If you prefer it that way, continue cooking for another half hour or so.
7. Remove the meat from the pot and cover loosely with foil.
8. Separate the vegetables from the liquid by pouring through a strainer. Reserve both the vegetables and the stock. De-fat the stock and discard the fat.
9. Add about 1/2 cup of the stock to the vegetables and puree with an immersion blender or food processor.
10. Use the stock to make gravy and then add about 1/2 to 1 cup of the pureed vegetables to the gravy if desired.