On the stove, heat the olive oil in a large fry pan over high heat and brown the beef cheeks well on all sides (if your pan isn't big enough you may need to do this in batches), then remove and set aside. See my notes for using the sear function if you have it.
2 tablespoon olive oil, 1 kg beef cheeks
To the same pan, add onion and carrot and cook until starting to soften.
1 brown onion, 1 large carrot
Add crushed garlic and tomato paste and continue to fry for 30 seconds.
1 tablespoon tomato paste, 4 garlic cloves
Add plain flour to the pan and stir to coat everything in flour then continue to fry for another minute.
¼ cup plain flour
Gradually add red wine and beef stock, stirring to remove any lumps and scraping up any brown bits from the base of the pan.
¾ cup dry red wine, 1¾ cups beef stock
Add remaining ingredients and bring to a simmer.
2 teaspoon fresh thyme leaves, 1 teaspoon fresh rosemary leaves, 2 teaspoon red wine vinegar, 1¾ teaspoon fine salt, a few grinds of fresh black pepper
Pour the hot stock and vegetable mixture into the bowl of the slow cooker.
Add in the beef cheeks as well as any resting juices, put the lid on and cook on low for 8 hours or until beef cheeks are tender.
Remove the beef cheeks from the slow cooker and cover to keep warm.
Pour the braising liquid into a small saucepan and simmer over medium heat until desired consistency.
Serve beef cheeks with sauce.