In a stand mixer, combine the salted butter, whole milk, active sourdough starter, organic all-purpose flour, raw honey, egg and yolk, and unrefined sea salt. Mix at medium speed until a shaggy dough forms, then knead for 10-15 minutes until smooth and elastic.

Transfer the dough to a greased bowl, cover it, and let it ferment in a warm area for 6-12 hours, until doubled in size.

Gently deflate the dough and turn it out onto a floured surface. Divide into 9-12 equal pieces and shape into logs.

Place shaped logs in a greased baking pan, cover, and let them rise for another 6-8 hours.

Preheat oven to 375°F (190°C). Whisk together the egg white and water for the wash, and brush it on the tops of the buns.

Bake for 20-25 minutes until golden brown and internal temperature reaches 200°F (93°C).

Let the buns cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.