Transfer olive oil, yogurt, vinegar, and yolk to a bowl and mix well with a fork. Add the flour and the salt and mix just until a ball of dough forms. Add 1-2 tablespoons of extra flour if dough is sticky.
Divide the dough into 6 mini tart pans and press with your fingers to cover the bottom and sides of the pans. Pierce the surface with a fork and put in the fridge for 10 minutes to cool.
Bake the crusts for 15-20 minutes or until golden (with this dough pie weights are not necessary, though you can use them if you want).
If you make this recipe into one large tart, you’ll have to add 10-15 minutes to the baking time.
For an 8-9 inches (20-23 cm) tart pan you will need the same quantities for the crust and double the quantities for the filling.
For a 10-12 inches (25-30 cm) tart pan, you’ll have to double the whole recipe (you may end up with some extra dough left. Don’t throw it away, mix it with 1-2 tablespoon grated cheese and make some savory cookies!)