In a large skillet over medium-high heat, add the vegetable oil.
When it begins to smoke slightly, add the beef and brown. Do in batches and do not cook through. Once browned, transfer the stew meat to the slow cooker.
Add onion, potatoes, carrots, and celery to the slow cooker on top of the beef. Sprinkle the garlic, thyme, oregano, bay leaves, salt and pepper over the top of the vegetables.
In a bowl or large measuring cup mix the red wine, beef stock, and tomato paste. Pour over the vegetables. Stir.
Place the lid on and cook on low for 8-9 hours or on high for 6-7 hours. If you are around, give it a few stirs during the cooking process.
For a thicker stew, mix 2 tablespoons flour and 1 tablespoon butter together with a fork. In the slow cooker, push aside some of the meat and vegetables. Gently whisk in the flour-butter mixture and cook another 15 minutes.
Serve and enjoy!