In a large mixing bowl, combine 2 1/2 cups flour and yeast. In saucepan, heat together milk, sugar, butter and salt just until warm, and butter is melted. Stir into flour-yeast mixture. Add condensed soup, sour cream, chives and tarragon. Beat at low speed to blend, then at high speed for 3 minutes. By hand, stir in enough of the remaining flour to make a moderately stiff dough.
Turn out onto floured surface and knead until smooth, 5-8 minutes. Place in greased bowl, turning once to grease surface. Cover; let rise until double in bulk, 50-60 minutes. Punch down. Cover and let rest 10 minutes.
Divide dough in half. Shape into loaves. Place in two greased 9 1/2 by 5 by 3-inch loaf pans. Let rise until double, about 30 minutes. Bake in preheated 400-degree oven for 30 minutes or until done. If crust browns too quickly, cover loosely with tent of foil last 10 minutes or baking time. Remove from pans and cool on racks.