Trim fat from meat. In a small bowl stir together garlic, sage, salt, and black pepper. Pat garlic-spice mixture on the surface of the meat. In a 5-1/2- to 6-quart Dutch oven over medium heat brown roast on all sides in hot oil. Drain off fat. Sprinkle cayenne pepper on roast. Pour water over roast; add onion. Bring to boiling; reduce heat. Simmer, tightly covered, for 1 hour and 20 minutes.
Add fruit and vegetables to meat. Return to boiling; reduce heat. Simmer, covered, for 20 to 25 minutes more or until parsnips or carrots and apples are tender, adding water if necessary. With a slotted spoon transfer all to a platter, reserving juices in Dutch oven. Keep warm.
For gravy, measure juices; skim off fat. If necessary, remove some of the juices or add enough water to juices to equal 1-1/2 cups. Return to Dutch oven. In a small bowl whisk together the 1/2 cup cold water and flour until smooth. Stir into juices in pan. Cook and stir over medium heat until thickened and bubbly. Cook and stir for 1 minute more. Season to taste with salt and pepper. Stir in balsamic vinegar. Serve gravy with roasted meat, vegetables, and fruit. Makes 8 to 10 servings.