Did You Know? Trail Drive Cooks made their sourdough biscuits without yeast. At the beginning of a drive, the cook would mix up a batch of batter and let it ferment in a jar for a day or so. The sourdoughs were made each morning by adding soda and lard to this fermented batter and then cooked between hot coals in a Dutch oven. The amount of batter removed each day to make the sourdoughs was replaced with more flour, salt, and water so that the fermenting process was ongoing during the drive. Trail hands often joked that a cook who made the desirable "light" doughs was always adding blueberries or raisins to their batter just to keep the gnats from flying off with them!
The critical factor in making light sourdoughs was calculating how many coals were placed below and above the oven. Here's an easy calculation when cooking with a Dutch oven. Figure 2 coals per inch of oven diameter. Then place 2 more coals than the oven size on the lid, and place 2 less than the oven size under it.
So if you are cooking in a 12-inch oven, you use a total of 24 coals. For the number of coals underneath, you would subtract 2 from 12 for 10 coals and on top: 12+2 for 14 coals.