Mix together ripe sourdough starter, all-purpose flour, granulated sugar and water. Knead the levain until it forms a cohesive ball. Set in a liquid measuring cup and cover for 10-12 hours until the levain has doubled in size and the top is rounded.

Mix Dough: Warm the milk in the microwave (about 1 ½ minutes full power) or on the stove. It should be around 90-100ºF, no warmer than that. To the bowl of a stand mixer with a dough hook, add the ripe levain, warmed milk and melted butter. Add the sugar, egg, salt and most of the bread flour. Turn on the dough hook and knead for a few minutes. Add the remainder of the bread flour as needed. The dough should be tacky, not overly sticky and should all cling to one side of the bowl (or away from the edges depending on your mixer). Knead for a total of 8-10 minutes until the dough is smooth. If mixing by hand, knead for 10-15 minutes.

Bulk Fermentation: Put the dough in a container and cover. Set the dough in a warm, 78-80ºF place for 4 hours. Take the temperature of the dough as needed to make sure the dough temperature stays right around 78-80ºF. This temperature is optimal for fermentation.

At the end of about 4 hours, the dough should be puffed up and feel very elastic. If it doesn't feel this way, let it bulk ferment for another half hour and check again.

Overnight Refrigeration: At this point, after the bulk fermentation has finished, cover the dough and put it in the refrigerator. Proceed with the recipe the next day, shaping and proofing the rolls before baking. This allows you to time the rolls for breakfast or brunch if desired. If you prefer to shape the rolls and bake them the same day, skip the overnight refrigeration and proceed with the recipe or see the recipe notes for other make-ahead options.

Mix up the Filling: Use a rolling pin to crush the freeze-dried strawberries into a fairly fine powder. To a small bowl, add the melted or very soft butter, granulated sugar, freeze-dried strawberries and flour. Mix together until it forms a thick paste. Set aside.

Prepare Strawberries: Wash and dice strawberries until you have about 300 grams worth. Take half of the diced strawberries, about 150 grams worth, and place in a small bowl. Add 20 grams of granulated sugar and mix together. Cover and refrigerate for after the rolls are baked. The remaining 150 grams of strawberries will be sprinkled on top of the strawberry rolls before being rolled up.

Shaping: Prepare 9 by 13 pan with parchment paper or use a non-stick pan. Roll the dough out into an approximate 16 by 12 rectangle. Spread the strawberry filling all over the dough with your fingers, making sure to spread right to the edges of the dough. Sprinkle diced strawberries over the dough. Starting with the dough closest to you, roll up the strawberry rolls and pinch together the seam. Flip the roll over, seam side down. Cut the long log of strawberry roll dough into 8 equal pieces. Place the rolls in the baking pan with two in the middle of the pan and three on each side of the pan, snuggling all 8 rolls together.

Proofing: Cover the pan and let rise in an 80-85ºF place until puffed up and risen, about 3-4 hours. Do not bake these rolls if they have not risen.

Baking: Pre-heat the oven to 350ºF. Bake for about 28-30 minutes until baked all the way through.

Cream Cheese Frosting: Using a hand mixer, whip together softened butter and cream cheese. Add the powdered sugar, heavy whipping cream, vanilla extract, and salt. Whip together for 2-3 minutes, scraping down the sides of the bowl as needed. The frosting should be light and fluffy.

Spread frosting over the tops of the strawberry rolls while they are still warm. Take the sugared strawberries from the fridge and top each strawberry roll with about 2 Tablespoons of strawberries. Enjoy!