Preheat the oven to 400 degrees F.
Season the shoulder with salt and pepper. Place on a baking sheet and roast for 1 hour. Reduce the temperature to 300 degrees F and continue to cook for 3 hours, or until the meat falls off the bones. Remove from the heat and cool completely.
In the cup of a blender, combine the egg, lime juice, mustard, chili paste, and sesame oil. Season with salt and pepper. Process until smooth. With the blender running, slowly drizzle in the oil and blend. The mixture will be thick. Season with salt and pepper. Remove, cover and refrigerate for at least 1 hour. The mixture will keep for up to 2 days. Slice the roast pork.
To assemble, slice the bread in half. Spread the chili mayo over both halves of bread. Layer the pork over one half of the bread, set the other half aside. Continue layering with the carrots, cucumbers, scallions, cilantro and jalapeno. Place the remaining half on top and press slightly. Slice the sandwich into individual pieces and serve.
Yield: 8 servings