1. Peel the red onion and the garlic cloves. Then slice the onion finely and chop up the garlic in small bits. In a large and high pan pour a little olive oil and place it over medium-high heat until hot. Add the garlic and onion. Season with a pinch of pepper and salt.
2. Stir and gently cook the onion and garlic for 4 minutes. Then add the drained mussels to the pan.
3. Give the mussels a very good stir using a slotted spoon and cook them for 3 minutes. Then pour in the dry white wine.
4. Stir the mussels well again and cover the pan. Cook the mussels for another 6 to 8 minutes or until they are all open and cooked in the end. Shake the pan regularly. Once the mussels are cooked, add the freshly chopped parsley to the pan.
5. Check the seasoning and add extra pepper or salt to taste if necessary. Stir one last time. Then scoop the cooked mussels and onion in large bowls and drizzle with the remaining white wine and mussel juice. Serve the mussels hot.