Mix the Dough:

1. In a small bowl or liquid measuring cup, mix together the sourdough starter and water. Add the beaten egg and mix well. Mix in the cooled melted butter. Set aside.
2. Whisk together the flours and sugar in a large bowl. Hold the salt.
3. Pour the sourdough/water mixture over the dry ingredients and mix well until fully incorporated. Cover and let rest 20-30 minutes.
4. Sprinkle salt over the dough and dissolve with 10-15 grams of water. Using wet fingers work thoroughly into the dough.
5. Cover the bowl and let rest at warm room temperature for 4-6 hours. Perform 2-3 stretch and folds every 30 min for the first hour to hour and a half. If the dough is really sticky, you may need to sprinkle some flour on the counter before performing the stretch and folds.

Cold Ferment Overnight

1. At this point, you can continue to shaping or place the dough in the refrigerator overnight. If you give the dough a cold ferment, the next day, take the dough out and allow it to warm up to room temperature for 1-2 hours before shaping the rolls.

Shape the Rolls:

1. Preheat the oven to 350 degrees F (175 degrees C). Grease or line a baking sheet with parchment. (I recommend parchment)
2. Punch down the dough, and divide it into 10 equal pieces, about the size of a golf ball. (My dough weighed 592 grams / 10 = ~59 grams each)
3. Using your hands or a rolling pin, flatten each piece into a small square or rectangle, about 4-4.5 inches in length. Place 3 slices of pepperoni down the center of each dough square, overlapping the slices. Place another row of 3 slices next to the first. Roll the dough around the pepperoni slices, pinch the edges closed, and place the rolls on the prepared cookie sheet.
4. Bake the rolls in the preheated oven for 14-16 minutes. until the bottoms are lightly browned and the tops are barely golden. (I baked the rolls about 18 minutes total, rotating the pan several times for even baking.)