Ingredients

• 3/4 cup whole-wheat flour
• 3/4 cup all-purpose flour
• 1/2 cup cornmeal (preferably stone-ground)
• 2 1/2 teaspoons baking powder
• 1/2 teaspoon baking soda
• 2 teaspoons packed light brown sugar
• 4 teaspoons dried green peppercorns, coarsely crushed, divided
• 1/2 teaspoon table salt
• 1 stick cold unsalted butter, cut into pieces
• 2/3 cup well-shaken buttermilk
• 1/2 teaspoon kosher salt
• 1 large egg, beaten

Instructions

1. Whisk together flours, cornmeal, baking powder, baking soda, brown sugar, 2 teaspoons peppercorns, and table salt in a bowl. Blend in butter using a pastry blender or your fingertips until mixture resembles coarse meal. Add buttermilk and stir just until a dough forms. Turn dough out onto a floured surface and gently knead 6 to 8 times. Cut into 5 pieces, then chill, covered with plastic wrap, 10 minutes.
2. Preheat oven to 350°F with racks in upper and lower thirds.
3. Mix kosher salt and remaining 2 teaspoons peppercorns in a small bowl.
4. Roll out 1 piece of dough on a well-floured surface with a floured rolling pin into a 15- by 4-inch rectangle (1/8 inch thick). Lightly brush with egg, then prick all over with a fork. Sprinkle with about 1/2 teaspoon salt-and-pepper mixture.
5. Cut crosswise into 12 strips and arrange 1/8 inch apart on a parchment-paper-lined baking sheet. Repeat with remaining dough.
6. Bake, switching position of sheets halfway through, until golden-brown and crisp, 20 to 25 minutes. Cool crackers slightly, then transfer to racks to cool completely.