Serves 4 to 6 as an appetizer

After cleaning mussels (see notes above or follow link), place in a large pot with a tightly fitting lid and do not add any liquid or seasoning. Cover the pot and cook over high heat for 5 to 6 minutes, shaking the pot occasionally. Remove from the heat and allow to cool enough for you to handle the mussels. Remove the from the shells, and discard the shells as well as any mussels that did not open.

Whisk together the oil, vinegar, mustard, salt, and pepper. Add the mussels and the remaining ingredients, stirring gently to combine. Refrigerate for at least 1 hour, or until ready to serve. Serve on a bed of lettuce leaves, garnish with additional parsley and lemon slices.