In a Dutch oven, heat the oil over medium heat. Add half the beef and cook until evenly browned, stirring occasionally. Transfer the browned beef to a plate. Brown the remaining beef. Pour off and discard the drippings. Return the first batch of beef to the Dutch oven. Season with the thyme, salt, and pepper. Stir in the broth, wine, and garlic. Increase the heat and bring to a boil. Reduce the heat and simmer, covered, for 1 1/2 hours. Add frozen vegetables and cook for 30 minutes, or until the beef and vegetables are tender. Put the cornstarch into a cup. Add the water, stirring to dissolve. Stir the cornstarch mixture into the beef mixture. Increase the heat to high and bring to a boil. Boil for 1 minute, stirring constantly.