This is a stunning show stopper. There are several steps but all are pretty simple. 

• For the pastry:  Blitz the flour in a food processor with the zest and the chilled butter until it looks sand.  Add the sugar and salt. Mix the yolks with a tbsp of chilled water and add to the flour mixture. Mix only until you can form a ball. If it’s too dry add a second tbsp. water and mix again. Wrap in clingfilm and flatten to create a thick disk. Refrigerate ½ hour or until firm. 
• For the filling: Measure the juice from the fruits. It should be 300-350ml worth of juice. If less then juice some more. Mix in a pan with the zest, cinnamon, and maple syrup. 
• Peel and roughly chop the apples. Add to the pan. Bring the mixture to a boil, uncovered, and cook over low-medium heat for 15-20 minutes until the apples soften. Once soft, crush with a fork and stir in the marmalade. Set aside.
• For the topping: Bring the water and sugar to a boil in a wide, shallow pan. Simmer, uncovered, stirring often for 10 minutes until syrupy. Carefully add the sliced tangerines to the pan and simmer for 10-15 minutes, turning them once or twice. Once most of the syrup has been absorbed and they start to turn golden, gently remove, slice by slice, and place them on a tray lined with baking parchment – or they will stick! 
• Preheat oven to 175°C. Put the chilled pastry between two pieces of baking parchment and flatten with a rolling pin to 3-4mm thick. Transfer into a lined 26 cm round tart tin, trim the edges and gently pierce the bottom with a fork.  Cover the dough with greaseproof paper and fill with baking beans. 
• Bake for 15-18 minutes. Remove the paper and baking beans and return to the oven for a further 5 minutes.
• Once the base has cooled, pour in the apple filling and cover the top with the caramelized tangerines. Sprinkle with pistachios to serve. Best made and eaten on the same day.