Gan Bian Si Ji Dou (干煸四季豆)

Green beans are approximately 90 percent water. In hot oil, the surface water boils off first. The cells under the skin lose pressure, and trapped steam lifts the skin into blisters.

When the surface is dry, its temperature rises above 100 °C. Maillard reactions and caramelisation then start on the sugars in the skin.

The wrinkled skin has more surface area and many small folds. A small volume of sauce stays on the beans and does not pool in the pan.

One layer is necessary. Beans that overlap hold steam against each other and do not blister. 360 g of beans fits in one layer in a 28 cm pan.

Pork mince and fresh shiitake both release water in the pan. While water remains, the pan stays near 100 °C and nothing browns.

When the water is gone, the sound changes from a boil to a sizzle. The temperature rises, the fat renders, and the Maillard reaction starts.

Fresh shiitake is approximately 90 percent water. Add it at the start, with the pork. Its water then leaves during the boiling phase and does not delay the browning.

The glutamate and nucleotides in that water do not evaporate. They stay on the meat.

Glutamate comes from the suimiyacai, the soy sauce and the MSG. Guanylate comes from the shiitake. The umami receptor T1R1/T1R3 binds glutamate at one site. A nucleotide at a second site holds the receptor in its active shape. The taste is much stronger than the sum of the two.

This lets the dish use less suimiyacai and less soy sauce than the original. MSG is approximately 12 percent sodium by weight. Salt is approximately 39 percent.

Estimated sodium for the whole dish is approximately 2 g, or approximately 1 g for each serving. Nobody measured this. It is calculated from the salt figures stored on each ingredient. Light soy sauce (approximately 0.75 g) and suimiyacai (approximately 0.5 g) carry most of it. The 1 g of salt on the beans adds approximately 0.4 g.

Hu la (糊辣) is the aroma of dried chilli and Sichuan pepper fried to the edge of burning. It is also the base aroma of gong bao dishes.

The sugars and amino acids in the chilli skin react under heat. They make roasted and smoky compounds, such as pyrazines and furans. Capsaicin and the terpenes of Sichuan pepper, such as linalool and limonene, dissolve into the oil. The oil then carries them through the dish.

Past dark red, the chilli turns black and bitter. Use medium heat and count the seconds.

The whole peppercorns give aroma but lose much of their numbing in the hot oil. The ground pepper at the end puts the numbing back.

Acetic acid boils at 118 °C. On a pan wall hotter than that, much of it evaporates at once. The aged, malty compounds of the Chinkiang vinegar stay.

Add it in the last seconds. Long heat with acid replaces the magnesium in chlorophyll with hydrogen. The green then turns olive.