1. Fit your food processor with the dough blade attachment, and place all the quiche crust ingredients in the bowl of a food processor and process with 5 to 6 pulses. Continue processing until the dough becomes smooth and forms a ball.
2. Transfer the dough in the bowl and knead lightly just until it comes together by hand. Wrap your dough ball in wax paper or plastic wrap and chill it for about 2 hours in the fridge until it has set.
3. Meanwhile, make the filling : Heat 1 tbsp vegetable oil in a fry pan over medium heat, and fry garlic until fragrant. Add beef, mushroom and leek and cook until no longer pink. Add all the seasoning ingredients "B" to taste. Let it cook and set aside.
4. When it gets cold, add them in a medium bowl, and add all seasoning ingredients "A". Mix well to combine evenly using a spatula.
5. Pre-heat the oven to 200C degrees. Get the dough out from the refrigerator and, using a rolling pin, roll out the dough into a smooth circle shape on a well floured surface (see the photo). Line a pie pan, easing the crust onto the base. Trim the excess crust edges with scissors or knife.
6. Pour the egg mixture onto the crust, and bake for about 35 - 40 minutes.