Use these buns to make our Smoked Pulled-Pork Sandwiches.
In the bowl of an electric mixer fitted with the paddle attachment, combine warm milk, water, and sugar. Sprinkle yeast on top. Let stand until foamy, about 10 minutes. Add 3 egg yolks, salt, butter, cornmeal, and flour; mix on low speed for 2 minutes. Change to dough hook attachment; beat until dough is smooth, soft, and does not stick to your fingers when squeezed, about 5 minutes.
Transfer dough to a clean surface. Knead into a ball; place in a bowl brushed with oil. Cover securely with plastic wrap; let stand in a warm place until dough has doubled in size, about 45 minutes. Preheat the oven to 400 degrees. Line a baking sheet with parchment.
Punch back the dough, and divide into 12 balls (2 1/4 ounces each). On a clean surface, using the palm of your hand, roll dough gently, pressing down while rolling to shape into a 2 1/4-inch-diameter ball. Place on prepared baking sheet. Repeat rolling until all the dough is used. Loosely cover with oiled plastic wrap. Let stand in a warm place to rise for 10 minutes.
In a small bowl, combine remaining egg yolk and the remaining tablespoon milk. Brush tops of rolls with egg wash. Sprinkle rolls with cornmeal. Bake until deep golden brown, rotating pan once during baking, about 15 minutes. Remove from oven, and transfer to a wire rack to cool.
The oven is an excellent place for rising dough. Preheat to 175 degrees for 5 minutes. Turn off heat and let covered dough rise in warm oven. This cuts the rising time by almost one-third.