2) Pour the stock into a large saucepan, bring to the boil and then whisk in the polenta. Reduce to a simmer and cook for about 30 minutes, stirring frequently.
3) Grease a large baking tray with a little of the olive oil then pour in the cooked polenta to a depth of about 2.5cm. Allow to cool completely. When the polenta is completely cooled cut into circles using a 7cm to 8cm cutter.
4) Meanwhile brush the courgettes and aubergines with oil and griddle until nicely lined and cook through. Brush the tomatoes and peppers with oil then griddle until nicely lined on both sides.
5) Make a dressing by blending together the remaining olive oil with the spinach, rocket, lemon juice and garlic.
6) To serve, place a circle of polenta in the centre of each plate top with the griddled vegetables, add some artichokes, then drizzle over the dressing and sprinkle over a few capers, pine nuts and oregano.