Start by thinly slicing the apples as even as you can. Note that in order to prevent the apples from browning while slicing, place the slices in water mixed with 1 tbsp lemon juice.
When done slicing, drain the water and add another tbsp lemon juice, sugar, cinnamon, vanilla and salt. Mix well the slices until all of them are tossed with sugar and cinnamon. Set aside while you make the dough.
To make the dough, mix the flour with sugar and salt. Make a well in the center of the flour mixture then add the oil. Mix with your fingers until crumbles form.
Start adding the cold water 1 tbsp at a time until a smooth dough forms. Cover and refrigerate for 15 mins.
In the mean time, transfer the tossed apple slices to a saucepan on medium heat. Heat until slices are soft (10-15 mins) while stirring every now and then. Remove from heat.
Preheat your oven to 180°C and grease your 20 cm pie pan with a bit of oil.
When dough has chilled, press it firmly in the tart pan starting with edges then the center. Pierce with a fork and bake the crust alone for 10 mins.
Remove the crust from the oven and start layering the soft apple slices as you like. Bake in preheated oven for 45-50 mins until crust is golden brown. PS: Don't discard the juice of the apple slices because we will use it at the end.
Remove from the oven, let cool for 15 mins then brush the apples with the juice that resulted from when heating the apples. Slice and enjoooy!