Place yeast in a large bowl. Cover with warm water; let stand until yeast begins to soften, about 3 minutes. Add honey and tomato paste, and whisk until smooth. Stir in bulgur and buttermilk; let stand 20 minutes.

Stir the butter and salt into the bulgur mixture. Then stir in the whole wheat flour and about 1-1/2 cups unbleached white flour to make a stiff dough. Turn out onto a lightly floured surface. Knead for 15 minutes, adding more flour if necessary to keep dough from sticking. Transfer the dough to a lightly oiled bowl, turn once to coat and cover with plastic wrap. Let rise in a warm place until doubled in volume (about 1-1/2 hours).

Turn dough out onto a lightly floured surface; punch down and divide in half. Roll and pull each half until it resembles a loaf of French or Italian bread.

Sprinkle a baking sheet with coarse cornmeal and place the loaves on the sheet. Brush loaves lightly with water; cover loosely with a towel and let rise in a warm place until doubled in volume, 45 minutes to an hour.

Preheat oven to 400°F.

With a sharp knife, slash the surface of the loaves four or five times; brush again with water. Bake until crisp and hollow sounding when tapped with your finger, about 25 minutes. Cool on a wire rack.

Makes 2 loaves (13 slices each).