In a mixing bowl, combine flour, cornstarch, baking powder, salt, and black pepper. Gradually whisk in cold sparkling water until the batter is smooth and slightly thick.

Heat the Oil

In a deep frying pan or a deep fryer, heat the oil to 350°F (175°C).

Fry the Fish

Dip each fish fillet into the batter, allowing the excess to drip off. Carefully place the battered fillet into the hot oil and fry until golden brown (about 4-5 minutes). Remove and drain on paper towels.

Preparing the Fries

Cut and Soak Potatoes

Cut the russet potatoes into fries and soak them in cold water for at least 30 minutes.

Fry the Fries

Remove the potatoes from the water, dry them thoroughly, and fry in the hot oil until golden brown and crispy (about 5-7 minutes). Season with salt to taste.

Preparing the Coleslaw

Mix the Ingredients

In a large bowl, combine shredded cabbage, grated carrot, mayonnaise, apple cider vinegar, sugar, salt, and pepper. Toss until well mixed and refrigerate until ready to serve.

Making the Tartar Sauce

Combine Ingredients

In a bowl, mix together mayonnaise, relish, lemon juice, Dijon mustard, salt, and pepper. Adjust seasoning to taste.