Combine 2 cups flour, undissolved yeast, sugar, and salt in a large mixer bowl.
Heat milk, water, and oil to very warm (120o to 130oF); add to flour mixture.
Beat 2 minutes at medium speed of electric mixer, scraping bowl occasionally.
Stir in enough remaining flour to make a soft dough. Knead on a lightly floured surface until smooth and elastic, about 8 to 10 minutes.
Cover tightly with plastic wrap; refrigerate for 8 to 24 hours. Divide dough in half; form each half into a smooth ball.
Place on a large greased baking sheet; flatten each to a 7-inch circle. Cover; let rise in a warm, draft-free place until almost doubled in size, about 45 minutes.
Brush tops with egg white; sprinkle with sesame seed.
Bake at 400oF for 20 to 25 minutes or until done.
Remove from sheet; cool on wire rack about 1 hour before making sandwiches.
To assemble sandwiches:
Split loaves in half horizontally.
Top each bottom half with half of Olive Salad, spreading to within 1 inch of the edge.
Layer half of meat and cheese over Olive Salad; place tops on sandwiches. Cut each into 4 wedges.