To prepare the Sauce, blend the sugar, water, salt and soy sauce in a saucepan, bring to a boil then simmer 5 minutes. In a small bowl, mix the cornstarch and water to form a smooth mixture. Stir into the sugar-soy sauce mixture. Simmer over low heat until the mixture thickens, about 10-15 minutes.
Heat the oil in a pan and stir-fry the diced tofu over medium h