Heat oil in a large Dutch oven.
Add the onions and garlic and saute for 2 to 3 minutes until tender.
Add the beef roast to the Dutch oven and brown on all sides.
Sprinkle with basil, marjoram, pepper, salt, and lemon zest as you brown.
Try to distribute the seasonings evenly over the roast as you turn it. Once the meat is browned on all sides, add the lemon juice and beef broth.
Cover, and cook over a low to medium-low setting for 3 to 4 hours until the meat is fork tender.
Add the vegetables about 30 to 40 minutes before the meat is done to cook together.
Once the vegetables are tender, remove the meat and vegetables to a serving dish and set aside.
Mix the cornstarch and water together in a small bowl, and then stir the mixture into the juices left in the pot to thicken.
Spoon the sauce over the meat and vegetables.