Preheat oven to 275-degrees. In a bowl, combine sage, salt, pepper and garlic. Rub all over pork. Place pork in an uncovered roasting pan on the middle oven rack. Bake about 3 hours, or until your meat thermometer reaches 150-degrees.
While cooking, place sugar, cornstarch, vinegar, water and soy sauce in a small saucepan. Heat, stirring occasionally, until mixture begins to bubble and thicken slightly. Brush roast with glaze 3 or 4 times during last half hour of cooking. Pour remaining glaze over roast and serve. Serve with mashed potatoes and vegetables or your choice.
If you like more sauce, simply double the sauce portion of this recipe.