The base of jajang sauce is chunjang—the Korean version of zhajiang, Chinese black-bean paste—which is made of fermented soybeans, flour, and caramel color. Although it is salty, it is not as salty or funky as other Korean soybean pastes like doenjang. Chunjang is sour and earthy when raw, but transforms when stir-fried in a little oil. “It turns very savory, a little sweet, and nutty,” Maangchi explains. Once the paste is combined with more oil and onions over high heat, it takes on a smoky flavor and smell, which is an essential element to jajangmyeon. There is also a potato-starch slurry added to the sauce to help make it sticky, creamy, and glossy as it coats the noodles. “When you’re eating jajangmyeon, sticky sauce makes it not cool down so quickly. Everything should be well coated, stuck together, and saucy so it stays hot and you can enjoy it until the last bite,” says Maangchi.