01 - Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.
02 - Pat salmon fillets dry with paper towels, season both sides with salt and pepper, and place skin-side down on the prepared baking sheet.
03 - Coarsely pulse pistachios in a food processor. Add gluten-free breadcrumbs, orange zest, parsley, and a pinch of salt; pulse just to combine.
04 - In a small bowl, whisk together fresh orange juice, Dijon mustard, and olive oil.
05 - Brush the orange glaze evenly over the tops of the salmon fillets. Press the pistachio mixture firmly onto the glazed tops to form an even crust.
06 - Bake for 12 to 15 minutes, or until the salmon flakes easily with a fork and the crust is golden brown.
07 - Serve immediately, garnished with optional orange wedges, extra pistachios, or fresh parsley as desired.