Start by peeling the potatoes and cutting them into thick chips. Rinse them under cold water to remove excess starch, then pat dry with a paper towel.

In a small bowl, mix together the mayonnaise, capers, lemon juice, and dill or parsley. Adjust seasoning to taste, then cover and set aside.

In a bowl, combine the flour, baking powder, salt, and pepper. Gradually add the cold sparkling water, whisking until smooth.

In a deep frying pan, heat vegetable oil over medium-high heat until it reaches 350°F (175°C).

Carefully add the potato chips to the hot oil in batches. Fry until golden brown and crispy, about 6–8 minutes. Remove with a slotted spoon and drain on paper towels, seasoning with salt.

Dip each fish fillet into the batter, allowing excess to drip off. Carefully place the fillets into the hot oil and fry for 5–7 minutes until golden and cooked through. Remove and drain again on paper towels.

Plate the crispy fish, alongside the golden chips. Garnish with fresh herbs and serve your homemade tartar sauce on the side.