Place water in a large bread bowl, add yeast, and stir. Add whole wheat flour and 1 cup white flour and stir well, then stir 100 times in the same direction to develop the gluten (one minute). Let this sponge stand for 1/2 hour to 3 hours, covered. Sprinkle salt over the sponge, then add another cup flour and stir. Continue adding flour and stirring until you can stir no longer. Turn dough out onto a lightly floured surface and knead thoroughly, about ten minutes, until dough is smooth and easy to handle. Clean out bowl, oil lightly, and return dough to bowl. Cover with plastic wrap and let rise in a convenient place for 2 to 3 hours. When the dough has more than doubled in volume, push down gently and turn out onto a lightly floured surface. Divide the dough into eight equal pieces and shape each into a flat oval shape, approximately 4x8" long. Leave these flat disks out on the work surface and cover with plastic wrap to let rise for approximately 20 minutes. Place quarry tiles or large baking stone on a rack in the lower third of your oven, leaving a 1" space between the tiles and the oven wall to allow air to circulate. Preheat oven to 450~. Five minutes after the oven has preheated, begin shaping the first bread. Place a small bowl full of cold water by the edge of your work surface. Using your fingertips, first dip them in the water and then, beginning at one end of the disk of dough, make tightly spaced indentations all over the surface of the dough, so that it looks pitted, though not pierced through. Now stretch the dough gently into a long oval strip by draping it over both hands and pulling them apart gently. The dough should stretch and give, and after several tries will extend to make a long oval about 12" long with attractive stretch marks along it from the stretched indentations (hence, the name "snowshoe bread"). Place the bread back on the work surface, sprinkle with a pinch (less than 1/8 ts) of black onion seeds, then using both hands, place the bread directly on heated quarry tiles or stone. While the bread bakes, begin to shape the next bread. Cooking time for each bread is approximately 4 minutes. You will soon develop a rhythm so that you can bake two breads side by side across your oven, one going in when the other is half done. When done, breads will have golden patches on top and a crusty browned bottom surface. To keep breads warm and soft, wrap them in a cotton cloth five minutes after they come out of the oven. Serve warm or at room temperature.