Preheat the oven to 425 degrees F. Lightly dust a cookie tray with some flour and set aside.
In a large bowl combine the flour, baking soda, cream of tartar and salt. Lightly mix through with a fork.
Add the egg to the buttermilk and whisk together until blended. Pour into the flour mixture and mix gently with your hands until the dough starts to come together. It may seem dry but it will become a ball.
Dump the dough out onto a table dusted with some flour. Gently knead until the dough is a round ball shape.
Lay it onto the cookie sheet dusting the top with a little more flour.
Take a very sharp serrated knife and cut a small cross on the top of the dough.
Place it in the oven and bake for about 35 minutes and it becomes golden brown.
Let cool on a wire rack before slicing.