ounces/55 grams self raising flour (divided) if you not have self tasing flour than you can use all-purpose flour and add 1 tsp baking powder and 1/4 tsp salt ), ounces/55 grams cornstarch, Sea salt,, Black pepper,, sparkling water, fish fillets (thick, white fish, preferably sustainable cod, tilapia, pollock, or haddock), potatoes (peeled), quart/1 liter vegetable oil (or olive oil for frying), real Mayonnaise, finely chopped dill pickles, dill (fresh or frozen), OR 1 Tbsp finely chopped fresh parsley, lemon juice