Give yourself about 30 minutes to assemble the soup. The vermicelli takes about 15 minutes to cook to al dente so do that first. Taste one before draining in a colander, then rinse under cold water and set aside to dry.
While the vermicelli is cooking, bring the soup up to a rolling boil and, using two spoons, spoon little crab meatballs into the soup. When the meatballs look cooked through, reduce the heat to a very low simmer.
Add tofu puffs to the soup. Slice your pork shoulder and, if using, pork loaf. Warm them in the soup. Let simmer while you prepare your bowls.
Heat up your bowls and prepare your vegetable toppings.
Assemble the bowls by adding noodles first, then pork, shrimp, and tofu puffs. Ladle the soup on top, ensuring every bowl gets an even amount of tomatoes and crab.
Enjoy immediately, with toppings.