Preheat your oven to 375°F (190°C).

In a large pot, add a splash of white wine and bring it to a gentle simmer. Place the fresh mussels in the pot, cover it, and steam for about 5 minutes until the mussels have opened. Discard any that remain closed.

Carefully remove the mussels from their shells, keeping half of the shell intact for each mussel. Place the shells on a baking sheet.

In a mixing bowl, combine breadcrumbs, minced garlic, grated Pecorino cheese, chopped parsley, mint, and finely chopped onion. Drizzle in olive oil, and lemon zest and juice. Season with salt and pepper.

Spoon the breadcrumb mixture onto each mussel half. Arrange them back onto the baking sheet.

Bake the mussels in the preheated oven for approximately 10 minutes until the topping is golden and crispy.

Remove the mussels from the oven and let them cool slightly. Garnish with fresh parsley before serving.