Ingredients
Coarse salt
1 pound wrapped heart mustard (also called dai gai choy), trimmed, small leaves left whole, and large leaves halved lengthwise
1 quart homemade or low-sodium store-bought chicken stock
2 pounds mussels, scrubbed well and beards removed
6 tablespoons Thai green-curry paste, or to taste
1 quart unsweetened canned coconut milk, stirred
4 lime wedges, for serving
Garlic chives (also called ku chai) or fresh cilantro, for garnish (optional)
Preparation
Bring a medium pot of water to a boil. Add salt to boiling water, then add cabbage; cook until crisp-tender, about 2 minutes. With a slotted spoon, transfer greens to a colander to drain.
Bring stock to a simmer in a large saucepan over medium-high heat, and add mussels. Cover pan, and cook until mussels open (check pan frequently after 2 minutes). With a slotted spoon, transfer mussels as they open to four large soup bowls, dividing evenly. (Discard any mussels that remain unopened after 5 minutes.) Divide reserved greens among the soup bowls.
Pour broth from pan through a fine sieve into a bowl, and rinse pan. Return broth to pan, and stir in green-curry paste. Bring to a simmer over high heat. Add coconut milk, whisking until incorporated. Bring to a bare simmer.
Divide broth among bowls, pouring over mussels and greens to reheat. Serve with lime wedges. Garnish with garlic chives, if desired.
