1. Season the chuck roast with the kosher salt, pepper and thyme (if you are sensitive to sodium, adjust to your taste or you can even leave the salt out altogether since you're adding broth).
2. Heat your pan (or if you can brown in your slow cooker, do it in that insert to medium high.
3. Add the vegetable oil and when it ripples and is hot add in the roast and brown, deeply, for 4-5 minutes on each side.
4. In your slow cooker add the carrots, potatoes and garlic.
5. Lay the beef on top, then add the beef broth and cover, cooking on low for 8 hours or on high for 5 hours.
6. In the last hour, mix your cornstarch and water and add it to the slow cooker to thicken the sauce or you can take the food out when done cooking, and add the leftover liquid to a small saucepan with the cornstarch/water slury mixture and cook on high for just 2-3 minutes until the liquid is thickened into a gravy.
7. Pour the gravy over the meat and garnish with parsley if desired.