Rub beef with oil, salt, pepper, garlic powder, onion powder, and thyme; sear (optional).
Whisk broth, Worcestershire, soy sauce, vinegar, and cornstarch (if using); taste and adjust.
Place onion, carrots, mushrooms, and garlic in crockpot; top with beef and sauce.
Cook on low 7–8 hours or high 4–5 hours (145°F–160°F internal).
Rest beef 10 min; slice against the grain.
Serve on a white ceramic platter with parsley, potatoes, and wine.