Mooncake (Lotus Paste and Salted Egg Yolk)

Variations

• Cantonese (Guangdong) mooncake: this recipe. A thin, tender shell around lotus paste and a salted yolk. It is what "mooncake" now means to most people.
• Suzhou-style: a flaky lard pastry in many layers, eaten straight from the oven with no resting stage at all. Fresh meat mooncake (鮮肉月餅) is that pastry around a savoury pork filling, sold hot to queues in Shanghai. It shares the name more than anything else.
• Snow skin (冰皮): unbaked, made from cooked glutinous rice flour and kept chilled. With no bake there is no resting stage either, so it is eaten the day it is made.
• Five-kernel (五仁): five nuts and seeds with candied peel. Famously divisive — enough that it is a running joke in Chinese-speaking countries.
• How many yolks: one is standard, two is 雙黃, four is 四黃. The count is more or less the price.
• Vietnamese banh trung thu: the same ancestor, sweeter, with a wider range of fillings — much the path French bread took to become banh mi.
• Same festival, another country: Korea's songpyeon is the Mid-Autumn cake there, but steamed, filled with sesame or beans, and with nothing to wait for (steaming).
• The rest of the Cantonese table: char siu bao, har gow, siu mai, Peking duck.
• Other sweet things: pastel de nata, tanghulu, dorayaki, taiyaki.

Tips

• The resting stage is the last step of the recipe. On baking day the shell is hard, pale and dry. Sealed in a box for two or three days, oil and moisture move out of the filling into the shell and it becomes soft and glossy. Assuming it failed and changing the recipe is the commonest mistake here. Build three days into the plan.
• Golden syrup has no real substitute. It is sugar boiled with acid until it splits into glucose and fructose, so it will not crystallise and it holds water hard — and that held water is what feeds the resting stage. Corn syrup behaves differently and honey is too strongly flavoured. Home-boiled syrup is aged a week at minimum, usually months (what sugar does).
• Lye water is there for colour. The Maillard reaction runs faster in alkaline conditions, which is how under twenty minutes of baking produces that deep brown. It also neutralises the acid in the syrup and softens the shell. Too much turns it bitter and almost black, so weigh it (browning).
• Three parts shell to seven parts filling. A thin shell is the mark of a well-made mooncake. Made thicker it is easier to handle, but the pattern blurs, it cracks in the oven, and the sweetness loses its balance (balancing flavour).
• Do not knead the dough. Developed gluten springs the pressed pattern back out and makes the shell tough. Stop when the dry flour disappears and let the rest do the rest (dough and gluten).
• Always tap the dusting flour back out. Flour left in the mould is behind most faint patterns. Turn the mould over and knock it before pressing.
• Leave no air when you wrap. Air between filling and shell expands in the oven and splits it. Push the dough up in stages and seal it by rolling it in your palm (wrapping and sealing).
• Egg wash thin, and on the raised parts only. Yolk only, loosened with water and sieved, with the brush squeezed almost dry. Pooled in the grooves it bakes them flat and the design goes (what your oven is doing).
• Keep the two bakes in that order. Five minutes sets the shape, then the wash goes on. Brushed on at the start, the dough rises through it and the pattern runs.
• Pre-bake the yolks only lightly. The liquor is for smell, the five minutes is for moisture. Cooked through now, plus the main bake, and they crumble.
• Loose paste collapses the pattern. It should hold its shape and not stick to your hands. If shop-bought paste is soft, dry it out in a pan first.
• Store sealed at room temperature. Past the two or three days it keeps a couple of weeks. Refrigerated, the shell hardens and the resting stops (serving temperature).
• It is a gift food, given by the box, which means the leftovers arrive by the box too. Cut in thin wedges with tea is how it was meant to be eaten in the first place (reviving leftovers).
• Treat the Yuan uprising legend as a story. The tale of messages hidden inside mooncakes to set the date of a rebellion is widely repeated but thinly sourced. As a festival food it is documented from the Ming period onwards.