Preheat the oven to 350 degrees. Meanwhile, make the Honey-Mustard Mayonnaise: Put the vinegar, egg, mustard, salt and pepper in the bowl of a food processor fitted with the stainless-steel blade or whisk attachment. Turn the machine on and, with the motor running, slowly drizzle in the olive oil, continuing to beat the mixture until all of the oil has been added and a good thick mayonnaise has formed. Add the honey and pulse the machine to blend it in. You should have about 1 1/2 cup, enough for many sandwiches; use liberally to taste, reserving the rest in a covered container in the refrigerator. To make the sandwiches: Bake the baguette in the preheated oven until it is good and crisp, about 10 minutes. With a bread knife, cut the baguette crosswise into two equal pieces; then, split each piece horizontally lengthwise in half, taking care not to cut all the way, so that it opens like a book. Coat the inside surfaces generously with the Honey-Mustard Mayonnaise. Layer the ham, cheese and Romaine inside each baguette half, adding sliced tomato, pickles and onion if you like. Close each sandwich securely and serve.