Bun Rieu (Vietnamese Crab and Pork Tomato Noodle Soup)

Together they produce a broth of unusual complexity that is simultaneously sweet, savory, and funky in ways that fish-sauce-based soups are not. Small river crabs are pounded whole, shell and all, in a mortar, then mixed with water and strained through a sieve to extract a turbid, intensely crab-scented liquid. This liquid is heated gently over low flame until the crab proteins coagulate into a soft, custard-like mass that floats to the surface, forming the crab cake that defines the dish. Tomatoes are added to the simmering broth and break down over time, tinting it red and contributing a fruity acidity that balances the crab richness. Mam tom, the fermented shrimp paste, is kept tableside and stirred in individually according to each diner's tolerance for pungency. A single spoonful transforms the broth into something considerably more intense and complex. Rice vermicelli provides a neutral base, while fried tofu puffs absorb broth during cooking and release it in each bite. Morning glory greens add a vegetable counterpoint. In Hanoi, bun rieu vendors typically specialize in this one soup, ladling hundreds of bowls from a single pot each morning before selling out by noon.