Heat olive oil in a large skillet over medium-high heat.
Add beef cubes in batches and brown on all sides, about 3-4 minutes per batch. Transfer browned beef to the crock pot.
In the same skillet, add chopped onion and sauté for 3 minutes until softened.
Add minced garlic and sliced mushrooms to the skillet and cook for another 5 minutes until mushrooms release their moisture and begin to brown.
Transfer the onion, garlic, and mushrooms mixture to the crock pot.
Pour beef broth and red wine into the crock pot.
Stir in tomato paste, dried thyme, dried rosemary, salt, and black pepper.
Cover and cook on low for 6 hours, or until the beef is tender.
About 30 minutes before serving, mix all-purpose flour with cold water to create a slurry.
Stir the slurry into the crock pot to thicken the sauce.
Cover and cook on high for an additional 30 minutes.
Taste and adjust seasoning if needed.
Serve hot, garnished with chopped fresh parsley.