Stir-Fried Shrimp and Cashews over Wrapped Heart Mustard

This dish is adapted from a chicken stir-fry developed by Yu Wen-Shen and Huang Hsien some years ago at the Hilton International Taipei. The mustard has an assertive radishy edge that is balanced by the sweetness of cashews and shrimp. Although it is seasoned forcefully, the egg binding mellows the dish, making it milder and silkier than most stir-fries. Save the leaves to sliver into egg drop soup—whether Chinese-style or alla romana.