Oil Tofu Puff and Glass Noodle Soup

Oil tofu puff and glass noodle soup is one of the four soups historically known among Shanghainese food writers as the city's 'four great street soups' — alongside curry beef soup, the double-rack gluten-and-tofu-skin combination known as shuang dang, and chicken-and-duck blood soup. The grouping reflects a specific Shanghai street-food ecology that took shape during the Republican era and the early decades of the People's Republic, when lane-side soup stalls served inexpensive, nourishing bowls to factory workers and residents on their way to and from work. Oil tofu puffs — deep-fried cubes of firm tofu that blister into spongy, broth-absorbent pillows — were a frugal protein source; glass noodles added bulk. The soup's endurance as a street fixture owes as much to its economics as to its flavour: a small stall could prepare the broth and tofu in advance and have bowls ready in under a minute.

The oil tofu puff is the star: it collapses gently under the spoon, releasing a rush of absorbed hot broth into the mouth, followed by the tofu's own beany softness. The glass noodles are slippery and neutral, acting as a smooth foil. A dab of house chilli paste on the surface adds the telltale Shanghainese frisson of mild heat.

Deep-frying firm tofu at 180–190°C rapidly evaporates surface moisture, causing the outer protein matrix to set into a rigid golden shell while steam pressure from inside creates an open-celled, sponge-like interior. This porous structure — with a surface area far larger than unfried tofu — makes each puff a highly efficient broth absorber: capillary action draws hot stock into thousands of microscopic cavities as soon as the puff enters the soup. Glass noodles made from sweet potato starch (high in amylose) remain firm even after extended simmering because the long, tightly packed amylose chains resist gelatinisation breakdown; they soften but do not turn mushy, making them ideal for soups with long holding times on street stalls.