First make the pie crust. In a medium sized bowl mix the flour, salt and light olive oil using a pastry blender. Once mixed, add the water so that the flour mixture is moistened, and continue mixing with your hands or using a fork until the mixture is consistent and does not stick to the sides of the bowl. Make a ball and wrap it in a cloth. Put the wrapped mixture in the refrigerator for at least 45 minutes.
Preheat the oven to 400ºF. Next, remove the dough from the refrigerator, and with a rolling pin, spread it over a floured flat surface. Place the dough in a 22cm diameter glass oven dish. Make sure that you have rolled out the dough well so that it covers the base and edges of the oven dish. Prick the dough with a fork to prevent it swelling. Bake the dough for around 15 minutes or until it is slightly golden. After this time, remove it and allow it to cool.
To make the lemon filling, first reduce the oven temperature to 180 degrees Celsius and beat the egg yolks using a fork. Next, in a medium casserole dish, mix the panela sugar and cornstarch. Gradually add 1 ½ cups of water. Cook on a medium heat and stir the mixture until it boils and thickens. Remove the mixture from the heat.
Add the oil, lemon zest and lemon juice to the mixture. Beat together with a pastry blender. Place the mixture in a deep bowl and cover with a clean dishcloth so that it does not lose all its heat. Set aside.
To make the meringue, beat the egg whites with the cream of tartar in an electric mixer on full speed until foam emerges. Next, add the panela sugar to the mixture and beat again at full speed. Continue beating until the surface of the mixture is shiny, the sign that the panela sugar has dissolved and that it has mixed properly with the rest of the ingredients. Now repeat the previous step for the vanilla, beating until the meringue is consistent and creamy.
Fill the pie crust which was cooling with the lemon cream. Make sure that the mixture is spread evenly over the whole base. Then spoon the meringue on top until the whole surface is covered.
Put the oven dish in the oven for 20-25 minutes or until the meringue is golden. Lower the temperature of the oven if necessary.
Leave the lemon pie to cool for one hour, and then ensure it is in the refrigerator for at least 4 hours before serving it.