How to Make It
In a medium bowl, mix the water with the yeast and let stand until foamy, about 10 minutes. Stir in the flour. Cover loosely and let stand overnight.
In a large bowl, mix 1/4 cup of the water with the yeast and sugar and let stand until foamy. Add the yeast mixture, the remaining 1 cup of water and the olive oil. Stir in the flours and salt until a dough forms. Turn the dough out onto a lightly floured work surface and knead until smooth. Place the dough in a large, oiled bowl, cover with plastic wrap and let stand until doubled in bulk, about 3 hours.
Place a baking stone on the bottom of the oven and preheat the oven to 450°. Punch down the dough and divide it into 4 pieces. Flatten each piece into a round. Cover them with plastic and let rise until puffy, about 30 minutes.
Sprinkle a pizza peel with cornmeal. On a floured work surface, with wet hands, flatten each round into an 8-by-10-inch oval. Make 6 or 7 deep grooves with your fingertips down the length of each oval. Sprinkle the ovals with the nigella seeds. Slide the ovals onto the peel, then onto the hot stone in the oven. Bake until crisp on the bottom, about 10 minutes. Serve warm.