1 cup warm water
3 tablespoons buttermilk, warmed
2 teaspoons active dry yeast
3 tablespoons sugar
2 eggs, separated
2 2/3 cups bread flour
2/3 cups all-purpose flour
1 1/2 teaspoons salt
2 to 3 tablespoons butter, softened
In a small glass bowl or measuring cup, combine the water, buttermilk, yeast and sugar, and let stand about 5 minutes, until foamy.
In a large mixing bowl, whisk together the flours and the salt.
Add the butter, and rub the mixture between your fingers until the texture is crumbly but still dry.
Lightly beat one of the eggs, and add it to the flour mixture, along with the buttermilk mixture. Use a metal spoon or dough scraper to bring the ingredients together into a dough.
Transfer the dough to a lightly floured work surface, and knead until elastic, about 10 minutes. Or use a stand mixer with a dough hook for this process. The dough will still be sticky to the touch.
Shape the dough into a ball, and place it in a lightly greased mixing bowl.
Cover with plastic wrap, and set it aside in a warm place to rise for 2 hours.
Lightly dust the work surface with flour, and with a sharp knife, cut the dough into 8 pieces.
Gently roll the pieces into balls, and place them about 2 inches apart on a baking sheet lined with parchment paper.
Lightly coat the roll in oil, and cover them with a piece of plastic wrap.
Let them rise for an additional 1 to 2 hours, or until doubled in size.
Heat the oven to 400 F.
In a small bowl, beat the remaining egg with a teaspoon or so of water.
Uncover the buns, and brush with the egg wash.
Bake on a center rack for 10 to 20 minutes, rotating halfway for even browning.
Allow to cool completely before serving.
