Pat beef dry and season with salt and pepper. Heat oil in a large skillet over medium-high heat and brown beef in 2 batches for about 8 minutes total; transfer to a 6-quart slow cooker.
Pour wine into the skillet, scrape up browned bits and simmer for 3 minutes. Stir in broth and tomato paste, then pour over beef.
Add mushrooms, potatoes, carrots, onion, garlic, thyme and bay leaf. Cover and cook on low for about 8 hours until beef reaches at least 145°F and both beef and potatoes are fork-tender.
Remove bay leaf. Stir cornstarch with cold water and mix into the cooker.
Cover and cook on high for 10 to 15 minutes until the sauce lightly thickens.
Divide beef, vegetables and sauce among 6 shallow bowls.