In a large mixing bowl, stir together the flour, semolina and salt. Stir in the dried yeast (or crumble in the fresh yeast). Make a well in the centre of the flour mixture and pour in most of the water along with the olive oil. Bring the dough together with your hands or a wooden spoon. As the flour is incorporated, the dough will start to take shape. Add the remaining water if the dough feels tight or hard.
Turn the dough out onto a clean surface and knead for 10 minutes, or until it is smooth