Bring a saucepan of water to the boil, add a pinch of salt. Blanch carrot, cauliflower and celery for a minute. Drain and leave aside.
Brush a pie mould lightly with olive oil. Roll out the pastry to line the mould. Allow some excess pastry dough to drape over the rim of the mould. Prick all over with a fork.
Beat up eggs, seasoning and milk. Heat olive oil in a saucepan and sauté garlic, onion and leek until fragrant. Add blanched vegetables and capsicum.
Combine all the vegetables with milk mixture then pour into the pie shell. Do not fill to the brim, but just 80% full.
Bake in preheated oven at 200°C for 25-30 minutes or until the top of pie is set or golden brown. Remove from oven and serve hot.
To prepare pastry dough: Sift flour into a mixing bowl. Add salt and mix in egg and butter. Stir to combine. Pour in ice-cold water and mix lightly into a soft dough. Leave aside for 5-10 minutes before use.