Sift the semolina and flour together twice on to the table top. Make them into a mound. Plunge your fist into the centre of the pile, pour in a little tepid salty water. Begin to knead together – you are trying to achieve the same consistency as bread dough, stiffer, but no softer. After about 25 minutes you should have reached the right texture. Cover the dough with a damp tea cloth.