Prepare baking sheet: Cut a large piece of parchment and lay on a flat baking sheet.
Stir dry ingredients: Add flours, baking soda, salt, and sugar (if using) to a large mixing bowl. Stir together with a spoon.
Add wet ingredients: Pour sourdough discard and water into the dry mixture.
Mix: Stir until there are no dry patches left and a thick sticky mixture is made. Add raisins and mix into the dough. Mixing with hands is helpful for this thick dough.
Knead: Place dough onto a work surface. Continue to mix and knead with hands for 1-3 minutes to check for dry spots. Dough should be soft and smooth.
Divide: Divide dough into 6 equally sized or weight pieces.
Shape: Use hands to form each piece of dough into a round shape. Place the round balls of dough about 4 inches apart on the parchment covered baking sheet. Cover with plastic wrap.
Ferment: Leave the dough covered at room temperature for 6-10 hours (or overnight) to ferment and rise. It will expand and spread into a large round of dough.
Preheat: After that time has passed, preheat oven to 425º F.
Score: Uncover dough. Use a knife to cut an x on the top of each round of dough across the dough that is about ¼ to ½ inch deep in the center.
Optional step: Use a pastry brush to brush additional water on the top, in the cut x, and all around the sides of the rounds. Sprinkle some additional sugar all over the tops of the moistened surface, once baked it will add a nice color and sugary crunch on the crust.
Bake: Place baking sheet into oven and bake 15 to 18 minutes. The rolls/scones should have a golden brown crust on top and a toothpick or knife inserted into the center should come out clean.
Cool: Allow the breads to cool for about 15-30 minutes.
Serve: Enjoy fresh or cut in half and add your favorite spread, honey, or jam.