Scrub mussels well; discard any that are not tightly closed.
Put water and lemon slices in a large saucepan; add mussels and bring to a boil. Simmer over low heat 3 to 5 minutes or until mussels open. Remove mussels from pan and reserve liquid. Discard any mussels that are not open. Cool mussels and liquid.
Meanwhile, stir together vinegar, oil, bell pepper, onion, parsley, TABASCO® Green Sauce, garlic, and salt in a medium bowl.
Remove mussels from shells, reserving half of shells. Add 1/3 cup cooled liquid and mussels to vegetable mixture and mix well. Cover and refrigerate at least 2 hours, stirring occasionally.
To serve, place mussels in shells and spoon a small amount of marinade on top.
Makes 4 servings.