Combine flour, sugar, salt, and baking soda in the bowl of an electric mixer fitted with the paddle attachment. Stir to combine.
Combine milk, water, and oil in a medium bowl. Whisk to combine.
With the mixer running, pour wet ingredients into dry ingredients. As soon as the mixture comes together, switch attachment to a dough hook, and mix until dough is smooth and no longer sticky. Do not over-mix.
Cover bowl with plastic wrap, and set aside at room temperature for 1 hour.
Place a pizza stone on a top rack of the oven, positioned approximately 6 inches below the broiler. Preheat oven to 500 degrees F for at least 30 minutes.
Divide dough evenly into 5 pieces. On a lightly floured surface, roll each piece into an 8-inch circle.
Turn oven to broil. Carefully slide one circle of dough onto the preheated pizza stone, and broil until bread is bubbled and golden brown, about 2 to 3 minutes. Watch carefully, as the bread can burn very quickly. Repeat with remaining dough rounds.
Brush the warm bread with melted butter, and serve immediately.