Defrost the roast overnight in the refrigerator, in a bowl of cold water, or in the microwave according to microwave settings. Once the roast is thawed rub with seasoned salt, thyme, and rosemary.

In a large skillet, over high heat, add oil and heat until the oil and the pan are hot. Lay the roast into the skillet to sear for 1 minute on each surface, until the roast is browned all over.

Once browned, lay the roast flat in the bottom of the crock-pot. Add stock to the same skillet the beef was seared in. With a wooden spoon stir the stock over medium-high heat, to get the flavorful bits off the bottom of the pan, about 1 minute.

Pour the stock into the crock-pot. Add peeled and cut carrots, peeled and cut potatoes, chopped onion, chopped celery, and pepperoncini with the liquid from the container.

Cover the crock-pot and set on high for about 7 hours, or until the vegetables are tender and the beef falls apart.

Remove the liquid from the crock-pot using a baster, and transfer into a small pot, over medium-high heat.

In a small bowl dilute the cornstarch and water. Pour into the small pot and stir, cook for about 2 minutes, until the stock thickens into a gravy. As the gravy cools it will become thicker.

Pour the gravy over the beef before serving.