Trim any skin off the fish filets and make sure they are very dry to begin. Season the fish with salt generously, and set aside into the fridge to dry out slightly for 1 hour.

Set aside about 2 Tbsp of flour in a shallow dish then add the remaining flour, cornstarch, baking powder and spices to a bowl. Whisk to combine then whisk in the club soda till the batter is smooth. This batter should be runny but fall in ribbons, similar to the consistency of crepe batter. Add more club soda if it seems too thick, or a little flour if it needs some more body.

Peel the potatoes and cut each into thirds lengthwise, then cut those planks into three thick strips. Bring a large pot of water to a boil and add in the 1 Tbsp vinegar. Boil the potatoes for 5-8 minutes until they are just fork tender but not falling apart, then remove to a tray and set aside.

Preheat your oil to 315 F. Fry the boiled potatoes for 4-5 minutes just until pale golden and crisped on the outside. Remove to a tray lined with paper towels and turn the heat up on the oil until it reaches 325 F.

Place a round of parchment paper into the oil to prevent the fish from sticking to the bottom of the pan. Dip the fish into the plain flower you set aside and then into the batter. Fry until golden brown and cooked through, about 6-8 minutes. Remove to a tray and immediately season with salt.

Return the fries to the oil and fry until golden brown and crispy, about 4 more minutes. Season with salt and serve alongside the fish.