Open-crust chicken and mushroom pie

Instructions

1. Process flour and spread in a food processor until mixture resembles breadcrumbs. Add egg yolk and 2 teaspoons water and process until dough just clings together, adding a little more water if necessary (see Kitchen tip). Turn dough out onto a lightly floured surface and knead for 30 seconds. Shape into a disc and cover with plastic wrap. Refrigerate for 30 minutes.
2. Meanwhile, heat oil in a large non-stick frying pan over medium heat. Add onion and chicken and cook, stirring, for 5 minutes or until onion has softened and chicken is lightly browned. Add mushrooms and garlic and cook, stirring, for 3–4 minutes or until vegetables are just tender. Add tomatoes and zucchini and bring to the boil. Reduce heat and simmer, uncovered, for 15 minutes or until mixture has thickened. Stir in chopped tarragon. Cool for 15 minutes.
3. Preheat oven to 220°C or 200°C fan-forced. Roll pastry between 2 sheets of baking paper into a 24cm round. Remove top layer of paper and place remaining piece with pastry on a large baking tray.
4. Sprinkle polenta over pastry. Spoon chicken mixture onto pastry round, leaving a 4cm border. Fold pastry edges to form a border. Sprinkle with parmesan and bake for 25–30 minutes or until pastry is golden and crisp. Serve sprinkled with extra tarragon.