Sour & Spicy Sweet Potato Noodles (Suan La Fen)
Three different ingredients make these hot-and-sour sweet potato noodles quite spicy. One of them, the green Sichuan peppercorns, can be tough to find and there isn't an easy sub, so leave them out if you like.
Tips: Sichuan chili oil: A Sichuan spice blend is infused into the oil, which is mixed with chile pepper flakes (not fried). The oil can be strained and the flakes used separately.
Zhenjiang black vinegar: Sometimes labeled "Chinkiang," this delicately sour rice vinegar seasoned with sugar and salt is used in virtually all cold Sichuan noodle and vegetable sauces, and in other sweet and sour dishes.
Sichuan peppercorn oil: A fragrant finishing oil infused with essential oils extracted from the Sichuan peppercorn. It has a smoother taste than the whole spice yet enough zing to wake up the mouth.
Green Sichuan peppercorns: With a distinctly lemony taste that is different from red Sichuan peppercorns, green ones complement fish, chicken and vegetables. China has only recently started to export them, so they are a little harder to find.
Sweet potato glass noodles: Long, clear, chewy noodles made from sweet potato starch. While bland on their own, the noodles absorb the flavors of whatever they're cooked in.