Popiah (Fresh Spring Rolls in a Griddle-Rubbed Wrapper)

Variations

• Taiwan's runbing: in Taiwan popiah is called runbing (潤餅), and the filling changes by region. Korean Wikipedia notes that the north fills it with stir-fried ingredients, a savoury sauce and peanut powder, and the south mostly with blanched vegetables, sugar and peanut powder.
• Fried popiah: in Malaysia and Singapore, where it became part of Chinese-Malaysian and Chinese-Singaporean cooking, fried popiah is a very popular street food. Fry it and chả giò's rule comes back: "Half the job is getting water out of the filling."
• Bought wrappers: if the slapping and rubbing are too much, use shop-bought popiah skins or spring-roll wrappers. If you are not frying them, steam spring-roll wrappers for a minute to soften them.
• About the photograph: it shows three rubbed wrappers at a stall being dressed with sauce, lettuce, sprouts, egg and peanut. The ragged, spread-thin edge is what a wrapper rubbed onto a hot plate looks like.

Tips

• Neither poured nor rolled. Korean Wikipedia says the wrapper uses a very thin, sticky dough, held in the hand and rubbed in a circle on a hot plate. Chunbing gets a thin wheat pancake from the opposite side: "The boiling water is there to put some of the gluten out of action, and the doubling is there to reach a thinness you cannot roll on your own." Popiah uses neither a pin nor a pair of discs. Its thickness is whatever the plate catches in one touch: a thin layer sticks to the iron, starts to cook, and is peeled away once it is done.
• Which is why the gluten is built as far as it will go. Chunbing puts part of its gluten out of action; this dough is as wet as a batter and still has to hang from the hand in one mass. As dough and gluten says of gluten, "it needs water to form, and movement makes more of it." There is already plenty of water, so what is left is movement — ten minutes of slapping.
• Do not oil the pan. The film has to stick for there to be a wrapper at all. Too cool and nothing sticks; too hot and it sets as it touches and holes. Work at medium-low and count on losing the first one or two while you find the heat. A stall cook usually works two or three plates in turn and turns out wrappers one after another.
• The filling is wet, so it is rolled at the table. Drained, this filling is still moist, and the wrapper is as thin as paper. Wrapping and sealing gives this as one of its answers for a parcel nothing cooks afterwards: "Keep the two apart until the last second." The parcel is assembled twice, and the second time is at the table. The popiah party Korean Wikipedia describes — the ingredients laid out and each guest rolling their own — is exactly that. Laying the lettuce down first keeps the wet filling off the wrapper too.
• Unfried, so the filling is not wrung dry. Gỏi cuốn gives the reason: "with no heat there is no steam and no pressure to hold." Draining off the liquid is enough.