In a large mixing bowl, combine 2 1/2 cups flour, yeast, sugar and salt. In a small saucepan, heat water and yogurt to 120-130. Add to flour mixture. Mix well. Add oil, herbs and enough of the remaining flour to form a stiff dough. Turn onto a floured surface; knead until smooth and elastic, about 6-8 minutes. Place in a greased bowl, turning once to grease top. Cover and let rise in a warm place until doubled, about 1 hour. Punch dough down; shape into two loaves. Place in two greased 8x4x2 inch loaf pans. Cover and let rise until doubled, about 1 hour. Bake at 375 for 35-40 minutes or until golden brown. Remove from pans to cool on wire racks. Yield 2 loaves. (32 slices).