Spring onion and crab tart

Place the butter and flour in a large mixing bowl and rub them together using fingers and thumbs until the butter is completely integrated, and the mixture has formed a crumb-like consistency. Add the egg yolk and water, and mix together into a dough. Knead the dough by hand for 1 min, wrap the ball of dough in cling film and leave to chill for 30 mins. Grease the tart dish. On a clean work surface dusted with flour, roll out the dough so it fits in the dish with a 2cm overhang. Prick the bottom of the pastry case with a fork several times, then leave to chill for 30 mins. Preheat the oven to 200°C/gas mark 6. Cover the pastry with baking paper, then fill with the baking beans. Bake for 10 mins, then remove from the oven and take out the beans and paper. Trim away any excess pastry from the rim, return the pastry case to the oven and cook for a further 5 mins. Allow to cool. Turn the oven to 180°C/gas mark 4. Cut the spring onions in half lengthways, then in half horizontally. Position them within the pastry case in a spiral shape. In a large bowl, whisk the eggs and double cream together and season with salt and pepper. Add the crab meat, then mix in the chopped garlic and mint. Add the lemon zest and juice, then season with pepper. Fill the pastry case with the mixture. Bake for 1 hr, covering loosely with a circle of tin foil when the spring onions start to brown. The filling should be firm and golden. Allow to cool slightly and serve, or allow to cool completely, then refridgerate and serve chilled.