In a large bowl, mix the shredded cabbage and grated carrots. In a separate bowl, combine mayonnaise, vinegar, sugar, salt, and pepper. Mix well and pour over the cabbage mixture. Toss to coat evenly and refrigerate until serving.

Make the Tartar Sauce

In a small bowl, combine chopped pickles, capers, lemon juice, Dijon mustard, salt, and pepper. Mix well and set aside in the refrigerator.

Prepare the Fries

Peel and cut the potatoes into thick fries. Soak them in cold water for at least 30 minutes. Drain and pat dry.

Fry the Potatoes

Heat vegetable oil in a deep fryer or large pot to 350°F (175°C). Fry the potatoes in batches until golden brown and crispy, about 5-7 minutes. Remove and drain on paper towels. Season with salt.

Prepare the Batter

In a bowl, whisk together flour, cornstarch, baking powder, and salt. Gradually add cold sparkling water until you have a smooth batter.

Fry the Fish

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

Serve

Plate the fish and fries together, serve with coleslaw and tartar sauce on the side.