Generously season both sides of the roast with salt and pepper.
Pour just enough oil into a Dutch oven to cover the bottom and heat over medium-high heat.
Brown the roast on both sides. Remove from the heat.
Add the beef stock or broth. If necessary, add enough water to bring the level of liquid halfway up the side of the roast.
Add the rosemary and garlic.
Cover tightly and place in preheated oven. Cook for 1 ½ hours.
Remove from oven and allow to stand for 10-15 minutes before slicing.
To make the gravy – Remove the roast from the pot. Place the pot over medium-high heat and bring the liquid to a boil. Dissolve corn starch in ¼ cup water and stir into boiling liquid. If desired, mash the softened, cooked garlic and add to the gravy.