Step 1

Heat oil in a 5 to 7 quart slow cooker using sauté function or in a large skillet over medium-high heat. Season beef with salt and pepper. Cook, turning occasionally, until browned on all sides, 10 to 12 minutes in a skillet or 25 to 30 minutes in a slow cooker; transfer to a plate. Add tomato paste and wine. Cook, scraping up any brown bits, 30 seconds. If using a skillet, add sauce to slow cooker.

Step 2

Whisk in stock, flour, and mustard. Add carrots, potatoes, mushrooms, onion, celery, garlic, and thyme; stir to combine. Add beef. Cover and cook until beef is tender, 5 to 6 hours on high or 7 to 8 hours on low.