Preheat oven to 450 degrees F (230 degrees C or mark 8).
Sift the flour, sugar, baking soda, and salt into a large bowl. Make a well in the center and pout in most of the buttermilk, leaving about ¼ cup (50 ml) in the measuring cup. Using one hand with your fingers outstretched like a claw, bring the flour and liquid together, adding more buttermilk, if necessary. Don't knead the mixture, or it will become heavy. The dough should be soft, but not too wet and sticky.
When the dough comes together, turn it onto a floured work surface and bring it together a little more. Pat the dough into a round about 1½ inches (4 cm) thick and cut a deep cross in it. Place on a baking sheet. (I lined mine with parchment paper.).
Bake for 15 minutes. Turn down the heat to 400 degrees F (200 degrees C or gas mark 6) and bake for 30 minutes more. When done, the load will sound slightly hollow when tapped on the bottom and be golden in color.
Rachel recommends turning the bread upside down for the last 5 minutes.