Coat an 11 × 9-inch baking dish with cold water and pour the polenta into it. Let the polenta chill completely in the refrigerator. Place a cutting board over the baking dish, then flip it over, letting the polenta settle onto the cutting board. Cut the polenta into 2-inch rectangles or triangles. Grill over a hot fire until the polenta has grill marks on both sides, or fry in plenty of vegetable oil until golden brown (how to fry). Serve hot.