In a large ziplock bag add the fish sauce, lime juice, soy sauce, sugar, crushed garlic, salt, and pepper. Squeeze the bag with your hands to mix well.
Trim the pork belly to remove any silverskin, fat or similar. Score the top (fat side) of the pork belly in a crisscross about every inch (2.5 cm). If the skin is still on reduce this to about 1/3 inch (85 mm) so it is easier to slice when cooked.
Place the prepared pork belly in the bag of marinade and place it in a chilled place for 24 hours. Occasionally shake up and turn to make sure there is even coverage and it doesn’t pool on one part of the meat only.
Preheat the traditional smoker to 275 degrees F (135 degrees C).
Add the pork belly then cook for 4 to 5 hours turning after 2 hours.Alternately: cook in a drum smoker hot and fast. Smoke at 300 degrees F (150 degrees C) for 3 hours, turning after 90 minutes.
The pork belly is ready when both surfaces have developed a crust and the internal temperature is around 190 degrees F (88 degrees C). Glaze the pork belly with hoisin sauce for the last 10 minutes on the smoker.
Pickled Carrot and Radishes
Prepare the vegetables if not already done. Shred (grate) the carrots. Cut into matchsticks or grate (shred) the radish.
In a non-reactive container add the vinegar, water, sugar, and salt then mix until the sugar and salt have dissolved. Add the carrot and radish then leave for 30 to 60 minutes before serving.
Rest the pork belly in foil for 1 hour before slicing. Slice about 1/4 inch thickness (6 mm).
In a small bowl combine the mayonnaise and sriracha until well combined. Put aside until needed.
Split the French rolls in half lengthwise then add in order the dressing, cucumber, thinly sliced jalapeno (to taste), sliced pork belly, pickled carrot, and radish, then finally garnish with the cilantro.