Preheat oven to 275°F (140°C, gas mark 1).
In a Dutch oven, heat the oil over medium high heat.
Season the venison shanks generously with salt and pepper, then add them to the pot to sear.
Sear the shanks, turning them so all sides get cooked, until very brown.
Remove from pot.
Add all of the vegetables except for 1 garlic clove, and sauté until they are softened, about 6-8 minutes.
Pour in the stock and scrape up any bits stuck to the bottom of the pot.
Add the shanks back in, cover, and put in the oven for 4 hours, or until the shanks are tender and the meat falls off of the bone.
Remove the shanks and shred the meat. Discard the bones.
Strain the broth through a sieve or a colander lined with cheese cloth and discard the solids.
At this point you can attempt to skim off the fat with a spoon, or you can put the broth in the fridge for 2-24 hours, then peel off the fat that solidifies on the surface.
Warm the broth back up if necessary, and add in the shredded meat.
Taste for seasoning and add any salt or pepper you feel is necessary. If you’d like it a little punchier, crush the last garlic clove into paste and stir it into the soup. Enjoy!