Mussels au Gratin

Preheat the oven to 425 degrees F (220 degrees C).

Scrape mussels under cold running water and remove beards. Discard any mussels that do not close when tapped.

Combine mussels, onion, wine, and pepper in a medium pot and bring to a boil over high heat. Reduce heat to medium-high and cook, shaking pot frequently, until mussels open, about 5 minutes.

Combine bread crumbs, parsley, and garlic in a small dish. Whisk oil and lemon juice together in a second small bowl.

Snap each mussel into 2 parts and place the shell with the meat in an oven-proof dish. Make sure no liquid remains on the shell; discard the empty shells. Spoon parsley mixture over the mussels and drizzle with the oil mixture.

Bake mussels in the preheated oven until topping is crunchy, about 10 minutes.