Rinse the fish under cold water and remove any bones. Soak in cold water, in a covered bowl in the fridge, for at least 36 hours changing out the water 4 times per day.
Cut the fish into pieces, remove the skin and press between paper towels to remove any of the excess water. This step is important because if the fish is not completely dry it is going to become a soggy mess in the frying pan. Set aside on a plate, uncovered and keep in the fridge to remain chilled.
Add the flour and baking powder to a large bowl, mix well to combine. Using a whisk, slowly add the beer and egg until a thick batter forms. Place in the fridge for around 30 minutes to become very chilled.
In a large frying pan, heat the oil over medium high heat (175C). Dredge the fish first in the rice flour, shaking of the excess and then dip in the batter and carefully place it in the hot oil. Make sure the oil is hot before adding the fish, otherwise you risk a soggy outcome.
Fry the fish until golden brown on each side then remove and drain on paper towels. You can place the fish on a baking rack over a tray in very low, warm oven to keep it warm and crisp until ready to serve. Serve with the Skordalia and beetroot to salad or horta.