Line a 20x30cm baking pan with baking paper. Bring 1 litre stock (chicken, beef or vegetable) and 2 tbs chopped herbs (thyme, rosemary) to the boil in a large saucepan or casserole pan over medium-high heat. Add 250g polenta in a thin stream, whisking continuously to prevent lumps.
Reduce heat to medium and continue to stir with a wooden spoon for 5 minutes until mixture has thickened. Remove from heat and stir in 1/2 cup grated parmesan. Pour polenta into pan and smooth surface. Cover surface with baking paper and cool for 15 minutes. Chill overnight.
Transfer polenta to a chopping board. Cut into chips. Heat vegetable oil in a large saucepan over medium-high heat. Cook polenta chips, in batches, for about 5 minutes or until golden. Drain on paper towel. Sprinkle with sea salt flakes and pepper. Serve hot.