Preheat the oven to fan 180˚C.
In a bowl, combine the breadcrumb with half of the peperoni, rocket leaves and garlic. Drizzle some oil and season with salt and pepper.
In an oven dish, lay the leeks, shallots, potatoes to create a bed for the fish.
Season with salt and pepper and drizzle with a little of oil and white wine if desired.
Take the fish fillets and place with the flesh up (skin on the vegetables).
Season with salt and pepper and sprinkle the breadcrumb mixture over.
Scatter the rest of the peperoni slices around the dish.
Transfer in the oven and bake for 15-20 minutes until the fish is flaky and cooked through.
Remove from the oven, scatter extra rocket leaves, and serve immediately using the vegetables on the base of the dish as vegetables.