Blend the chili paste ingredients in a mini food processor until finely ground and well blended. Heat a wok and add cooking oil. Stir-fry the chili paste for 5 minutes. Remove from the heat and set aside.
In the same unwashed wok, add a little oil and cook the shrimp topping. Then, add a small amount of chili paste, sugar, and salt. Pan-fry the shrimp until slightly browned. Remove from the heat, let them cool, and then slice them in half.
Add 15 cups of water to a pot and bring it to a boil. Then, add all the shrimp heads and shells, and simmer on low heat for about 2 hours or longer, until the stock becomes cloudy and has an intensely prawn flavor.
Strain the stock through a sieve and transfer it to another pot, discarding the shrimp heads and shells. Remove and discard any orange foam that forms on the surface of the stock.
Bring the stock to a boil again and add half of the chili paste. You can add more chili paste if you prefer a spicier flavor.
Add the pork ribs and continue to simmer over low heat for another 1 to 1.5 hours, or until the pork ribs are thoroughly cooked. Add rock sugar and salt to taste.
To serve, place a portion of yellow noodles, rice vermicelli, water convolvulus, and bean sprouts in a bowl. Ladle hot stock over the noodles and vegetables. If desired, add a few pieces of pork ribs. Top with sliced pork, sliced shrimp, egg quarters, and sprinkle with shallot crisps. Serve immediately, and add more chili paste to taste if desired.