Combine the Seasoning mix in a bowl and set aside.
Coat both sides of meat with olive oil. Sprinkle on a third of the seasoning mix onto each side. Sear both sides of the meat in a large skillet over medium-high heat. Transfer roast to slow cooker.
Place the vegetables in a large bowl. Drizzle on a little olive oil to coat vegetables. Sprinkle on the remaining seasoning mix. Pour these over the roast. Pour the beef stock in.
Cover and cook on Low setting for 9 hours or High setting for 5-6 hours.
Spoon out most of the cooking juices from the slow cooker, either remove the roast or use a baster. Transfer juices to a small sauce pan and bring to a simmer over medium heat on the stove. Whisk together the cornstarch with a little water. Blend into the pan juices while whisking continuously. Bring back to a simmer until thickened. Taste and adjust seasoning as needed.
Place the roast on a serving dish, spoon on the vegetables, ladle the gravy over, serve. Just that easy.