Lay the fish filets on a paper towel and pat dry. Season them generously with sea salt and pepper.
In a large bowl, mix the flour, baking powder, salt, black pepper and garlic powder. Then add the carbonated water and/or gluten free beer
Mix until you have a slightly thick, smooth batter. If it’s too thick, add a little more beer.
To prepare the oil: Add oil to a deep pot—about 3 inches full–and heat oil to 350 degrees F. Make sure the oil is at the right temperature. For this it is best to use a thermometer to monitor the oil temp (at least 350 and no higher than 375). If the oil is too hot, the fish won't cook fast enough before the coating is overly crisp. If the oil is not hot enough, the coating will be soggy/soft instead of crisp.
Place the dipped filets into the pot, don’t overcrowd them.
Fry for approximately 5-7 minutes or until internal temperature reaches 140 degrees, turning occasionally, until the batter is crisp and golden and the fish is perfectly cooked.
Once cooked, remove the filets from the hot oil and drain on paper towels for two minutes to get that carryover cooking and internal temp up another 1-2 degrees. You can keep them in a 200 degree oven while you make the chips but I like to make the chips first and keep them in the oven so the fish is the freshest.
Next, add your chips to the hot oil for 5 to 8 minutes or until golden. Remove the chips from the oil with a slotted spoon and allow to drain on another plate with a paper towel.
To make the tartar sauce, mix the mayonnaise with chopped pickles, parsley and dill, lemon juice, salt and pepper.
Serve the fish with the chips, mayonnaise dip and ketchup on the side.