Preheat oven to 425°F. Lightly flour baking sheet. Mix flour, caraway seeds, if using, baking soda and salt in large bowl. Mix in enough buttermilk to form moist clumps. Gather dough into ball. Turn out onto lightly flour surfaced and knead just until dough holds together, about 1 minute. Shape dough into 6-inch-diameter by 2-inch-high round. Place on prepared baking sheet. Cut 1-inch-deep X across top of bread, extending almost to edges. Bake until bread is golden brown and sounds hollow when tapped on bottom, about 35 minutes. Transfer bread to rack and cool completely.