2. 雪里红腌菜 (xuě lǐ hóng yān cài) - Salt Cured Potherb Mustard (Brassica juncea var. crispifolia)
This is another local treatment for mustard. It is exactly as described in the name. "雪里红" means "potherb mustard"; "腌" means "salt" and "菜" means "vegetable". Unlike the suancai above, this is dry cured, so the final product retains some crispiness, unlike suancai which has a more "cooked" texture. Whether or not it is available elsewhere, I don't know. Suancai is everywhere - I've bought it in London. Most Asian stores or markets should have suancai. If you can also find this one outside China, please let me know.