01 - Preheat the oven to 400°F. Line a baking sheet with parchment paper and lightly oil or spray it.
02 - Cut fish fillets into 1-inch bite-sized cubes.
03 - Whisk lemon juice, olive oil, Dijon mustard, salt, and pepper in a bowl. Add fish cubes and toss gently to coat. Marinate for 10 minutes.
04 - Combine panko breadcrumbs, grated Parmesan, sweet paprika, and dried parsley in a shallow dish.
05 - Remove fish cubes from marinade, allowing excess liquid to drip off. Roll each piece in breadcrumb mixture, pressing gently to adhere.
06 - Place coated fish bites on the prepared baking sheet. Lightly spray or drizzle with olive oil to promote crispiness.
07 - Bake for 16 to 18 minutes, turning once halfway through, until golden brown and fully cooked.
08 - Serve immediately with lemon wedges or a preferred dipping sauce.