Preheat the oven to 425°F. Line a baking sheet with parchment paper.
Place the salmon on the prepared baking sheet and evenly brush the mustard all over.
In a bowl, combine the parsley, breadcrumbs, garlic, orange zest, lemon zest, oil and a pinch each of salt and pepper. Stir to moisten the breadcrumbs evenly.
Cover the fish with the breadcrumb mixture, pressing firmly so it sticks to the mustard layer. Bake for 15 to 20 minutes, until the flesh is opaque in the center and flakes easily when gently tested with a fork. Serve. Any leftovers can be stored in an airtight container in the refrigerator for up to 2 days.