Combine the yeast and water in the bowl of an electric mixer. Let it rest until frothy, about 15 minutes. Using the paddle attachment, incorporate the flours into the yeast mixture. Beat in the salt and fennel. Switch to the dough hook and knead for 5 to 7 minutes. Remove the dough and place it into a lightly oiled bowl, turning to coat. Cover the dough with plastic and allow it to rise until doubled, about 1 hour. Punch the dough down, cover, and let it rise a second time until doubled, about 45 minutes.
Turn the risen dough out onto a work surface and divide it into 8 balls aproximately 3 ounces each. Place the balls on a floured cookie sheet, cover with a damp towel, and let them rest for 20 minutes. On a lightly floured work surface roll the balls out, dusting with flour as needed. Roll into 7-inch disks. Prepare a hot charcoal or stove top grill. Lightly brush the disks with olive oil. Place the disks, oiled side down on the grill. The breads will begin to rise almost immediately. When golden brown on 1 side, flip the breads over, brush again and cook until brown. Remove from the grill and serve warm.