Bun Rieu

Northern Vietnamese, traditionally made with paddy field crabs (cua dong) — small freshwater crabs that thrive in flooded rice fields. The dish dates to at least the late 19th century in the Red River Delta, when farming households pounded the whole crabs (shell and all) in stone mortars to extract their essence. Urban versions now use ground crab paste from a jar, which most Hanoi cooks will tell you is not the same.

Hanoi's red crab-paddy soup — freshwater paddy crab pounded shell and all, strained, simmered until the protein floats in clouds. Tomato, shrimp paste, tamarind do the rest. Eat with tia to (Vietnamese perilla).

A bright orange-red bowl with cubes of tofu puff floating on top, soft mounds of crab-and-egg paste suspended in a tomato-tinted broth, and round rice noodles below. The broth is sour-sweet from tomato and tamarind, salty from shrimp paste, and surprisingly light. The crab paste has the texture of soft custard, not meat — it should break apart when nudged with chopsticks. Fresh greens go on at the table.

The crab paste mounds form because of the protein in the pounded crab — when the paste hits hot broth, the proteins coagulate into soft curds that float, similar to egg-drop soup mechanics but with crab essence. Skip the pounding step and use only crab meat and you get crab-scented broth with no curds; the curds are the textural anchor of the dish, not a garnish.