Season the prime rib liberally with a dry rub of salt, pepper, thyme, and garlic powder
Heat a large skillet or pan over high heat and sear the prime rib until browned
Remove the prime rib from the skillet and place in the slow cooker
Pour in the beef broth and red wine
Cook on low for 6 to 8 hours or until the internal temperature reaches 135 F for medium-rare results
Once the prime rib is fully cooked, remove it from the crock pot or slow cooker and let it rest
Whisk together cornstarch and water in a small dish, ensuring no lumps
Cook the juices from the slow cooker and the cornstarch mixture in a saucepan and bring to a simmer. Ensure you mix continuously until the sauce thickens but is not sticky or too creamy
Serve the sliced prime rib and pour the red wine sauce on top for presentation and flavor