Mussel dishes are world-wide, and this recipe comes from the US, where they assure me that it only has 151 calories per serve! In Thailand mussels are cheap and plentiful.
Scrub and de-beard the mussels under running water. Prepare a steamer and place the mussels on the top. Steam the mussels for around seven to eight minutes, or until they have opened. Important: discard any that remain closed.
Meanwhile, in a medium sized saucepan, sauté onion in margarine, stirring over medium heat for two minutes. Stir in the garlic, sauté for 30 seconds, then add the tomatoes. Cook the tomatoes for two minutes, then add the wine and salt and pepper to taste.
Now quickly bring the tomatoes to a boil for around five minutes, until the sauce is thick. Stir in parsley and keep the sauce over very low heat.
Break off the empty half of the mussel shells and arrange the mussels on serving plates. Spoon some of the sauce over each mussel and serve immediately.