Steam mussels in white wine and 2 cloves garlic until they
open. Drain and cool.
In a large bowl or big jar, mix together the French mustard,
remaining garlic, salt and pepper, sugar, oregano and vinegar.
Add olive oil and mix
In a serving dish, toss mussels with 3/4 cup of this dressing.
Garnish with parsley, dill, onion.
Chill and serve.