Dissolve yeast and 1 teaspoon sugar in 1/4 cup warm water in small bowl. Let stand until foamy, 5 minutes.
Combine flours, salt, remaining sugar, yeast mixture in 12-cup processor with dough or steel blade.
With machine running, pour remaining 1-1/2 cups warm water slowly through feed tube. When ball forms, process 1 to 2 minutes. If dough doesnt clear sides of bowl, add more all-purpose flour, tablespoon at a time. If too dry, add water, 1 tablespoon at a time.
Place dough in large greased bowl, turning to coat. Cover loosely with plastic wrap. Bring large shallow pot of water just to simmering. Remove from heat. Place wire rack on top of pot. Place bowl with dough on rack; cover with a towel. Let rise 1 to 1-1/4 hours until doubled.
Punch dough down. Knead few turns on lightly floured surface. Divide dough in half; shape each into a 16-inch baguette. Place on lightly oiled baking sheet. Place on rack over very hot water in pot; cover with a towel. Let rise for 45 minutes or until doubled in volume.
Preheat oven to 425 degrees F. Slash tops of loaves diagonally lengthwise with single-edge razor blade.
Bake in preheated 425 degree F oven for 25 to 30 minutes or until golden and hollow-sounding when tapped. Cool on rack at least 30 minutes. Makes 2 loaves.