Preheat oven to 400 degrees Fahrenheit.

In one bowl, combine oil, mustard, salt, and pepper.

In a second bowl, combine panko crumbs, Parmesan cheese, and parsley flakes.

Dredge fish in oil mixture, then in crumbs. Arrange in a 9×13-inch baking dish.

Bake until fish flakes easily with a fork, about 20 minutes.

Serve warm or at room temperature.