Preheat the oven to 200oC.
In a small bowl, mix well butter, mustard and honey. In another bowl, mix breadcrumbs, pistachios and parsley.
Brush each salmon fillet with the mixture of mustard and honey and sprinkle with the breadcrumb - pistachio mixture.
Bake in the preheated oven for 12 to 15 minutes or until it becomes flaky. Season with salt and pepper and garnish with slices of lemon.