2½ teaspoons active dry yeast
4¾ cups all-purpose flour, plus more for dusting
2¼ cups whole wheat flour
2 tablespoons kosher salt
½ cup sour cream
Vegetable oil, for brushing
Grated cotija or parmesan cheese, for topping
Dissolve yeast in 3 cups warm water in a large bowl. Add both flours; mix with your fingertips until a shaggy dough forms. Cover bowl with plastic wrap and let rest at room temperature for 20 minutes.
Sprinkle salt over dough, then add sour cream; knead until well incorporated and dough pulls away from sides of bowl and holds together in a loose, wet ball, about 5 minutes (dough will be very soft; lightly moisten your hands to prevent sticking if needed). Cover bowl with plastic wrap and let dough rise at room temperature for 30 minutes.
Knead dough an additional 4 or 5 times to deflate. Do ahead: Cover and chill for up to 2 days. (Dough will develop in flavor and continue to rise slowly in refrigerator.) Alternatively, let dough stand at room temperature until doubled in volume, 3 to 4 hours (the warmer and more humid your kitchen is, the faster it will rise). Chill for 1 hour before grilling to make it easier to handle.
Build a medium-hot fire in a charcoal grill, or heat a gas grill to high. Divide dough into 8 equal portions. Generously flour a work surface. Working with 1 or 2 portions at a time (depending on how many flatbreads will fit on your grill), roll out dough or press with your hands into a ¼ -inch-thick shape.
Brush grill grate with oil. Grill flatbreads until lightly charred on one side and no longer sticking to grill, 2 to 3 minutes. Using a metal spatula, turn flatbreads and grill until cooked through, 1 to 2 minutes longer.
Top with cheese and your toppings of choice and serve immediately.
Cook's notes: Top the flatbread with cheese and vegetables, wrap it around grilled meat, or eat it straight off the grill. When making flatbreads, always work on a clean and well-oiled grill. And make sure to leave the dough on the grill long enough for it to take on a nice char (just like a steak).
"The Grilling Book: The Definitive Guide from Bon Appétit" edited by Adam Rapoport (2013 Andrews McMeel)