Heat oil in a countertop deep-fryer to 250 degrees F.
Rinse the potatoes in cold water and pat each chip with paper towels until absolutely dry. Poach the chips in the oil until cooked but not browned, 3 to 4 minutes. Scoop up the chips, shake off the excess oil and set aside. Turn up the heat on the fryer to 350 degrees F.
In a large bowl, mix together the flour, baking soda, vinegar and 3 heaping tablespoons salt until pasty. Add 2 cups water and whisk until there are no lumps. Refrigerate the batter for 15 minutes.
Preheat the oven to 200 degrees F. Fill a second bowl with flour and season with salt. Sprinkle the fish fillets on both sides with salt and pepper, then dredge in the flour, making sure each fillet is completely covered.
Working in batches, shake off the excess flour from the fillets and dip them into the cooled batter. Let excess batter drip back into the bowl before gently lowering the fillets into the fryer. Fry until the batter is golden brown and the fish is just cooked through but still tender and juicy, 4 to 5 minutes. Drain on a wire rack set over a baking sheet and transfer to the oven to keep warm.
When all the fillets are cooked, crisp the chips in the fryer until golden brown. Carefully shake off the excess oil and season immediately with salt.
Serve the fish and chips with malt vinegar and tartar sauce on the side.
When frying the fish, allow the oil temperature to return to 350 degrees F between batches to ensure the fillets have a crisp coating.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.
Recipe courtesy of BatterFish Food Truck, Los Angeles, CA