Set your Sous Vide to 185°F in a deep water bath (large saucepan, at minimum).
In a baking dish, marinate short ribs in 1/4 cup Worcestershire sauce, 1/4 cup beef broth, a sprinkle of fresh thyme and salt and pepper to taste. Set aside.
1/4 cup beef broth, a sprinkle of fresh thyme and salt.
Reduce heat to medium-low and add sugar and 1 tbsp Worcestershire sauce. Mix and simmer for 8-10 more minutes, until onions are golden brown.
Add minced garlic and cook for 1-2 more minutes.
In a plastic bag, place marinated short ribs, the liquid, and the caramelized onions, making sure they're evenly distributed.
Lay flat and seal the bag using a vacuum sealer.
Place the sealed short ribs in the water bath to cook for 24 hours.