Season the fish filets both sides with salt and pepper and dredge in 2 tablespoons flour. Set aside while you make the batter.

Add the remaining flour, 1 teaspoon salt, 1/2 teaspoon ground black pepper and baking powder to a large shallow bowl. While whisking, slowly pour in the beer until there are no lumps and it is the thickness of pancake batter.

To a high-sided heavy pan, add the oil to 1/3 full with canola oil and bring up to a temperature of 375°F/190°C.

Place a wire rack on a baking sheet and place in a 275°F/135°C oven.

Coat 1 fish filet in the batter and hold up to drain off excess. Holding the fish at one end, slowly add the fish to the oil. Hold it with most of it submerged for about 3-4 seconds so it does not sink to the bottom and stick. Submerge the whole fish and fry for 4-5 minutes, turning halfway until golden brown. Drain and put on the wire rack in the oven. Repeat with the other fillets.

While the fish is in the oven, turn down the heat under the oil until the temperature of the oil reaches 350°F/175°C.

Add the chips and fry, turning often about 8 minutes until golden brown. Drain and serve with the fish and peas.