Preheat the oven to 425ºF (220°C). Line a rimmed baking sheet with parchment paper.
Place the fish fillets on the prepared baking sheet and season with salt and pepper.
In a blender or food processor, combine the herbs, lemon juice, and mustard and blitz until chopped finely. Stir in the blitzed bread crumbs (or crackers or potato chips). Season with salt and pepper.
Sprinkle the crumb mixture over the fish fillets. Bake, uncovered, until cooked through, about 12 minutes, depending on the thickness of the fish fillets.
Drizzle olive oil over the fillets and serve immediately.