Season all sides of the short ribs with salt and pepper and set aside. Place flour in a gallon-size resealable bag then add the ribs and shake to lightly coat them in flour.
Next, heat oil in a large skillet over medium-high heat until the oil is shimmering. Add as many short ribs as possible without overcrowding the pan. Brown the ribs on all sides then add them to the slow cooker. Repeat with remaining short ribs.
Once the last of the short ribs has been transferred to the slow cooker, immediately add butter to the skillet and reduce the heat to medium. Add the onions and allow them to cook for approximately 3 minutes before adding the garlic. Allow the garlic to cook approximately 2 minutes then add the beef broth and red wine. Begin scraping the bottom of the skillet to remove anything that may be sticking.
Simmer the broth and wine for about 5 minutes before adding the remaining ingredients. Stir until combined then pour the mixture over the short ribs in the slow cooker. Set the slow cooker to low and cook for 8–9 hours.
When the ribs are fall-apart tender, carefully remove them to a serving platter and strain the cooking liquid through a sieve. Allow approximately 2 minutes for the fat to rise to the surface then skim it off with a ladle. Pour the liquid over the short ribs and serve. Enjoy!
Notes
Short ribs can get rather pricey in restaurants so why not enjoy them at home?