Season the roast with salt and pepper. In a separate bowl, combine the beef broth and Worcestershire sauce; set aside.

In a large nonstick skillet, heat 1 tablespoon of oil on medium-high heat. Add the roast and sear on all sides until it is nicely browned, about 5 minutes per side. Transfer the roast to the slow cooker and add the onions to the same skillet. Cook until the onions are translucent and begin to brown, about 5 minutes. Sprinkle in the minced garlic and add the flour and paprika to the skillet; saute for about 1 minute. Slowly whisk in the broth and Worchestershire sauce; cook for another minute.

Add the carrots and potatoes to the slow cooker, pour the sauce and onion mixture over the beef and vegetables in the slow cooker. Then add the thyme, rosemary, and bay leaf. Cover and cook on high for 5 to 6 hours or on low for 7 to 8 hours or until the roast is fork-tender.

During the last hour of cooking, mix together the water and cornstarch and add it to the slow cooker to thicken the sauce. Or you can transfer the cooking juices to a saucepan and add the water and cornstarch mixture. Cook for 2 to 3 minutes or until the sauce has become thickened. Then pour over the roast beef before serving.