Boil water. Pour into large mixing bowl and add in oats, butter, and honey and let soak for 30 minutes to an hour. Once water has cooled to comfortable to the touch add sourdough starter with a dough whisk stir until everything is combined.
Add in the flour and salt. Mix until the dough is a shaggy dough. The flour should all be combined, but the dough is not smooth.
Let dough rest for 45 minutes. Then do your first stretch and fold. The bread dough will be sticky the first time you do the stretch and fold, but will become less sticky each time you do the stretch and fold. Wet hands help the dough not stick to your fingers as much.
Stretch and fold with four turns 3 times total. (Stretching and folding is very soothing. Something about having your hands in dough. ha!) Let the dough rest 45 minutes and repeat 2 more times. Each time you do the stretch and fold the dough will become more smooth and stretchy.
Cover bowl and place bread dough in a warm place for bulk rise until dough has doubled. Anywhere from 3-8 hours depending on how warm your house is and have happy your sourdough starter is.
After the first rise, turn the dough out onto a floured work surface and gently press dough into a rectangle. Fold the dough over itself in thirds and and roll up into shape of a sandwich loaf.
Sprinkle top of loaf with some water and roll in some oats. Place the dough seam side down in a oiled loaf pan. Cover the loaf pan with tea towel or plastic wrap and let the dough rise for a second rise for another 2-3 hours at room temperature, or until it has doubled in size. You could let the dough rise in the refrigerator overnight instead for a more tangy flavor and bake the next day.
Preheat the oven to 375°F. Once oven is at proper temperature, score the loaf down the middle and bake the bread for about 40-45 minutes, or until the internal temperature of the bread is 195 degrees F.
Let the bread cool in the pan for a few minutes, then remove it from the pan and place it on a cooling rack to cool completely before slicing. Enjoy your delicious homemade honey oat sourdough sandwich bread!