Set your immersion circulator to 76 C (169 F).
If you have a vacuum sealer, use this technique. If not, you can do the same step with a Ziploc bag and the water displacement technique.* Add duck legs to the bag of your preferred method with the duck fat, fresh thyme sprigs and crushed fresh garlic.
Seal the bag and place it in your water bath for 14 hours. Make sure it is well submerged.
After 14 hours, take the duck out of the water, strain out of the bag right away and take the meat off the bones, discarding the skin and the bones. Make sure to strain the liquid fat properly and save for later use.**
Shred the meat a little smaller, roll it tight with cling wrap and put aside in either fridge or freezer for later use. You should get 2 rolls about 15 cm (6 inches) long and 5 cm (2 inches) in diameter.