Preheat oven to 200ºC In a food processor or a large bowl,mix 3 cups of the flour with salt,sugar,baking powder and baking soda. Cut the butter into the dry ingredients until the mixture is textured like cornmeal. Separately mix the eggs with the buttermilk,and stir all but 2 tbs.of this liquid into the dry mixture. Mix just enough to make a uniformly moistened dough. Dust a clean work surface with half the remaining flour,and turn the dough out onto the floured surface. Sprinkle the top with the rest of the flour,and with floured hands,gently push the dough into a circle about 1 cm thick.. Cut with a 5 cm or 8 cm biscuit cutter,and place buscuits close together on a grease and cormeal coated cookie sheet. You will get about dozen biscuits. Brush the tops of the biscuits with the reserved buttermilk egg mixture. Bake in the preheated oven until puffed and brown,about 15 minutes .Cool for a few minutes before serving.