Slice bread in half horizontally with a serrated bread knife.
Drizzle vinaigrette evenly on the cut side of each bread half. On bottom half, layer with tomato, ham, cheese, cucumber, and lettuce. Top with bread. If desired, trim edges with a serrated knife to square off sandwich.
Wrap sandwich tightly in plastic wrap and place in a two quart baking dish. Weigh it down with another two quart baking dish filled with cans or jars for at least 2 hours or up to 24 hours, refrigerated.