1. Rinse, scrub, and de-beard (remove the fibers or threads emerging from the shells) the mussels just before cooking, and discard any with loose or open shells. After steaming, discard any mussels that haven't opened. For an authentic touch, substitute two stalks of fresh lemon grass for the strips of lemon zest. Peel off the outer leaves, smash the stalks with the broad side of your knife, and cut the stalks into 2-inch lengths.
2. In a large stock pot (preferably 8 quarts or more) over medium heat, warm the oil. Add onion, garlic, ginger, chili, and 5-4 in strips of lemon zest and cook, stirring often, until onion is softened and fragrant, 3 to 4 minutes.
3. Add coconut milk, lime juice, and fish sauce, cover pot, adjust heat to medium high, and bring mixture to a strong boil. Remove cover, add mussels and 1/2 cup basil, stir to coat mussels with onions and seasonings, replace cover, and simmer over medium heat, stirring occasionally, until mussels are opened fully, about 5 minutes.
4. Add remaining 1/2 cup basil and cilantro, stir to distribute, and serve with some of the broth; garnish with lime wedges.
Source: Hannaford fresh Magazine, September - October 2007