Begin by lightly greasing two baking sheets and preparing your dry ingredients. Combine 2¾ cups (350g) bread flour, 3¼ cups (350g) barley flour, 1½ teaspoons salt, 1½ teaspoons sugar, and 1 packet (¼-ounce/7g) fast-acting dried yeast in a large bowl.
Add 3 tablespoons (40g) salted butter to the dry mixture and rub it in by hand until the mixture resembles breadcrumbs, or use a stand mixer for a quicker alternative.
Gradually add the 1¾ cups plus 2 tablespoons (approximately 450ml) tepid milk and water mixture in a steady stream while mixing, incorporating it fully to form a cohesive dough.
Once the dough has come together, knead it thoroughly until it becomes smooth and elastic. If using a stand mixer with a dough hook, this step takes approximately 2 extra minutes; by hand, you'll need to work the dough for several minutes until it reaches the desired consistency.
Turn the kneaded dough onto a lightly floured surface and divide it into 12 equal pieces. Shape each piece into a round roll by gently tucking the edges underneath to create surface tension, then arrange all 12 rolls on the prepared baking sheets.
Cover the shaped rolls with oiled plastic wrap and allow them to proof at room temperature until they have doubled in size, typically 1 to 2 hours depending on kitchen temperature.
When the rolls have finished proofing, preheat your oven to 425°F.
Remove the plastic wrap and bake the rolls for 10 to 15 minutes until they turn golden brown and sound hollow when tapped on the bottom. Transfer the finished rolls to a wire rack to cool completely before serving.
