2 packages dry yeast
1 1/4 cups warm water
1 cup sourdough starter (at room temperature)
1/4 cup granulated sugar
1 tablespoon salt
2 eggs, beaten
1/4 cup vegetable oil
5 1/2 to 6 cups unbleached flour, divided
Dissolve yeast in water in a large nonreactive bowl; let stand 5 minutes.
Stir in sourdough starter, sugar, salt, eggs, oil and 3 cups flour. Gradually add remaining flour. Turn dough out on a floured surface and knead until smooth and elastic (about 8 to 10 minutes). Place in a well-greased bowl, turning to grease top. Cover and let rise in a warm place (85 degrees F ), free from drafts, 1 to 1 1/2 hours or until doubled in bulk.
Punch dough down; divide in half and place on a floured surface. Roll each half into an 18 x 9-inch rectangle. Beginning at narrow edge, tightly roll up dough. Pinch seam and ends together to seal. Place loaves, seam side down, in greased 9 x 5 x 3-inch loaf pans. Brush top with oil. Cover loaves; let rise in a warm place (85 degrees F), free from drafts, about 1 hour or until doubled in bulk.
Bake at 375 degrees F for 30 to 35 minutes or until loaves sound hollow when tapped. Remove from pans; brush with melted butter.
Yields 2 loaves.