Yácài (芽菜) is one of Sichuan's most famous and distinctive food products. Made from the stems of a variety of mustard green, its fragrant and distinctive flavor is found in many of the region's dishes. Said to have been invented in the early 19th century, ya cai is just one of the family of preserved vegetables used in Sichuan's cuisine that includes zhàcài (榨菜), dàtóucài (大头菜) and others.
Yacai's primary ingredient is jièmòcài (芥茉菜), a type of mustard green native to southeast Sichuan. Four to five months after being planted, the mustard green plants are harvested in the ninth lunar month. The leaves are then discarded, the stems sliced into even strips, and the strips hung out on poles to dry.
The making of yacai is unusual among Sichuanese ingredients in that it demands two fermentation stages—others, such as doubanjiang (chili bean paste) and douchi (fermented black beans) require only one. Once sufficiently dry, the mustard green stems are mixed with salt and left to ferment in sealed containers for three to six months. Small ceramic pots called tutan are traditionally used.
Once this first stage is complete, the mustard green stems are boiled with brown sugar for eight to nine hours and then hung up to dry out once more. Next, star anise, Sichuan pepper, and other spices are added, and again, the mustard green stems are left to ferment in sealed containers for another three to six months.
In Chengdu's markets you can sometimes find un-cut yacai—long, straggly strips of green-brown vegetable, sold by weight—but mostly yacai is sold pre-chopped in small, sealed packages. When buying yacai, make sure to buy a brand based in Yibin, the most celebrated producer of this ingredient located about 250 km southeast of Chengdu. Once opened, you should store yacai in a sealed container in a cool, dry place.
Though a few different brands exist, by far the most common is the Sichuan Yibin Suimi Yacai Company (四川宜宾碎米芽菜有限公司), who apparently started the practice of selling chopped yacai—"sui mi" means "crushed rice," referring to the appearance of the company's bitty, pre-cut yacai.
Yacai is often mixed with pork for baozi stuffing and is also a vital ingredient in Yibin's signature dish, ranmian ("burning noodles"). But it is perhaps most famously used in one of Sichuan's most popular vegetable dishes, dry-fried green beans (干煸四节豆/gānbiànsìjìdòu). I've eaten countless different versions of this dish, but this one is my favorite.
Dry-fried Green Beans干煸四节豆
250g green beans
2 tablespoons yacai
1 tablespoon fermented black beans (dou chi), rinsed and drained
5 dried chili peppers, halved and seeds discarded
1 teaspoon Sichuan pepper (huajiao)
3 cloves of garlic, thinly sliced, and the same amount of ginger, thinly sliced
3 spring onions, cut into 3cm pieces
50g minced pork (optional)
Salt to taste
1. Top and tail the green beans, and cut into 5cm lengths.
2. Heat your wok, and add about a tablespoon of cooking oil. Once hot, add the pork and stir-fry for a few minutes until cooked through, and then set aside.
3. Add a tablespoon of oil to the wok, and once hot, add the beans, stir-fry for a couple of minutes, and then add another 1 to 2 tablespoons of oil. Stir-fry for another 3 to 5 minutes, or until the beans are tender. Remove from the wok and set aside.
4. Add another tablespoon of oil to the wok, and once hot add the garlic and ginger slices. Stir-fry on a moderate heat for about 30 seconds, and then add the chilies and Sichuan pepper. Stir-fry for another 30 seconds, taking care not to burn the spices, and now add the ya cai and dou chi and stir-fry for another 30 seconds.
5. Finally, add the spring onions (and the pork, if using), and return the beans to the wok. Stir-fry for another minute or so, add salt to taste, remove to a serving dish and serve.