Bring 1 litre water almost to the boil in a large saucepan over medium-high heat, add 2 tsp salt and gradually pour in the polenta in a steady stream using a whisk to stir the water, then stir continuously with a wooden spoon until polenta boils and becomes thick (10-15 minutes). Add parmesan and taste for salt – it generally needs quite a bit. Add a little more water in necessary; the polenta should fall off the spoon. Pour into a small oiled tray so polenta is 3cm-4cm deep and set aside to cool, then refrigerate until firm. This can be done a day ahead.
To serve, heat a char-grill over high heat until very hot, cut polenta into wedges and grill on one side until char marks appear (3-5 minutes). Serve warm with salad.