Heat oil on medium in large heavy skillet.
Lightly dust short ribs with the 4 tablespoon of flour
Brown short ribs lightly on all sides, about 8-10 minutes
Place short ribs in the slow cooker and discard all but about 2 tablespoon of the oil in the pan.
Add garlic and celery, carrots and onion to the skillet and cook and stir about 3 minutes, until the carrots begin to soften.
Add all-purpose flour to the skillet and stir to combine
Add the wine to the skillet, stirring to scrape up the bits on the bottom of the skillet. Cook for about 5 minutes until the wine is reduced and starts to have a syrup-like consistency .
Add stock to the pan and bring to simmer.
Pour stock mixture over meat in slow cooker.
Add tomatoes, bay leaves and ½ tablespoon thyme
Cover and cook 4-5 hours on HIGH or 7-9 hours on LOW. Transfer short ribs to serving platter. Discard bay leaves and stir remaining thyme into sauce. Season to taste with salt and pepper. Pour sauce over short ribs and serve.