Preheat the oven to 375 degrees F.
Rinse the pork and pat dry. Set the pork in a small baking dish, fat-side up, and add 1/2 cup water. Bake for 45 minutes. Reduce the oven temperature to 325 degrees F and bake until the meat is very tender, about 45 minutes longer. Let the pork cool, and then cover and refrigerate until chilled, at least 2 hours.
Cook 1/4 cup of the sugar in a saucepan over medium-high heat until it starts to melt, 2 minutes. Swirl the pan and continue to cook over medium heat until it is completely melted, 5 minutes. Occasionally wash down the side of the pan to release any sugar crystals using a wet pastry brush. Add the remaining 1/4 cup sugar and cook, swirling, until a richly brown caramel forms, 5 minutes. Turn off the heat and pour in 1/3 cup water. Turn the heat to high and cook, stirring, until the caramel is smooth. Remove the pan from the heat and stir in the vinegar, cilantro, syrup and chiles. Serve with the pork.