Fish and chips, homemade tartar sauce

Pasos

1. Peel the potatoes, cut them into thick fries, rinse them until the water runs clear, and dry them very carefully in a kitchen towel; they must be matte with no visible moisture.
2. Prepare the tartar sauce: chop the cornichons, capers, and shallot, finely chop the herbs, mix with the mayonnaise, lemon juice, and pepper, then chill in the refrigerator to let the sauce become fragrant.
3. Mix the flour, cornstarch, baking powder, salt, and pepper, then stir in the cold beer and cold sparkling water without over-mixing; the batter should coat a spoon while remaining slightly frothy.
4. Heat the oil in a large, stable pot or a deep fryer, and cook the fries a first time over moderate heat until they are soft and pale; drain them on a wire rack or paper towels.
5. Pat the cod dry with paper towels, salt it lightly, and dredge it in a dusting of flour to help the batter adhere; the surface must be dry to the touch.
6. Increase the heat of the oil, dip each piece of fish into the cold batter, let the excess drip off, and fry until you get a puffed, golden crust that sounds hollow when tapped.
7. Return the fries to the very hot oil until they are golden, crispy on the outside, and tender in the center; drain immediately and salt them while they are piping hot.
8. Serve the fish and chips immediately with the cold tartar sauce, lemon wedges, and a drizzle of malt vinegar to be added at the table to taste.