Blanch the pork twice: put the pork in a pot of water with 1/2 tbsp of salt, bring to boil and discard the water and impurities. Rinse the pork. Put the pork in the pot, add water to barely cover the meat and the sliced shallots. Bring to boil, reduce heat,let simmer for 45 minutes. To check if it's cooked, insert a chopstick in the meat, it should go in easily and with clear juice running. Remove the pork and pat dry. Reserve 1 cup of the stock to prepare the dipping sauce. When cool, put it in the refrigerator for around half an hour for easier slicing. Slice into thin slices.
In the same pot, bring the water back to boiling (add water if necessary), add the shrimps, reduce the heat to medium high. Cook the shrimps until they turn opaque and orangey/pinkish. Remove and drain. Slice the shrimps in half lengthwise.
Cook the rice vermicelli according to the package instructions and drain. (A tip: early in the day, you can soak the rice vermicelli in a large bowl of water (say for around 3-4 hours). When ready to cook, boil a big pot of water, add a pinch of salt, add the soaked rice vermicelli, and it would take around 2 minutes to cook). Drain the rice vermicelli, rinse with cold water, drain and set aside.
To assemble the rolls: Have all the ingredients ready, a large bowl of lukewarm water and a large plate or cutting board. Quickly dip the rice paper sheet in lukewarm water and put on a plate or cutting board. If you wish, cover the plate or cutting board with a clean kitchen towel to absorb any excess water or make sure to shake off any excess water if you have dipped for too long. At first the rice paper seems still a bit stiff but it will quickly soften. On one end (about 1/3 of the circle) layer the lettuce, fresh herbs, pork and vermicelli, align the shrimps next to the layered ingredients. Start rolling from the end while tightly tucking in the layered ingredients as you roll, then fold in the 2 sides to fully enclose the stuffing, then keep rolling over the shrimps till the other end. Tip: To save time, you can use 2 large plates or 2 cutting boards to alternate the waiting for the wet rice water to soften while wrapping another roll. When the shrimps are placed (the outer side of the shrimps are facing down against the rice paper), after rolling they would appear through the rice paper, which makes the fresh rolls more appetizing.
Repeat the same process for each roll.
To prepare the Vietnamese dipping sauce: In a small saucepan, heat the oil on medium high. Add the minced garlic and stir fry till golden (it would take less than a minute). Add the liquid (water or stock), hoisin sauce, peanut butter. Stir well and heat for around 4-5 minutes. Scoop into a serving bowl. Sprinkle the crushed peanuts and chili sauce on top.