STIR 2 cups milk with water in a medium saucepan. Boil, then slowly whisk in cornmeal until thickened but still loose, 2 to 3 min. Remove from heat and let polenta stand, to completely absorb liquid, 2 min. Whisk in remaining 1 1/2 cup milk, parmesan and salt. Serve polenta with cider-braised pork with caramelized onions.