Preheat oven to 425 degrees F. Coat a large baking sheet lined with foil with cooking spray.
Arrange potatoes on baking sheet and spray them with cooking spray. Season with salt and black pepper. Bake 25 minutes, or until golden brown and tender.
In a shallow dish, whisk together flour, baking powder and 1/2 teaspoon of salt. Whisk in milk and egg. Add cod fillets and turn to coat with batter. Add cod to a baking sheet that's been lined with foil and sprayed with cooking spray and bake 8 to 10 minutes, until golden brown and fork-tender.
In a small bowl, whisk together vinegar and honey to serve as a dipping sauce. Serve 1 pound of the fish and all of the potatoes with this meal. Reserve 1/2 pound fish for another recipe.