Whisk together the first three ingredients in a large bowl. Gradually blend in the oil. Stir in the olives and capers. Season the vinaigrette, to taste, with Adobo.
Cut off the top 1” of the bread loaf. Set aside. Hollow out the bottom and top halves of the loaf. Spread some of the olive and caper mix over the bread bottom.
Layer the meats and cheeses on the bread bottom. Top with the onions, then the arugula. Spread the remaining olive and caper mix on top of the sandwich and carefully cover with the bread top.
Serve the sandwich immediately, or wrap it tightly in plastic wrap and place it in the refrigerator a day before serving.
Cut the sandwich into wedges and serve.