Gather all the ingredients.
If making the optional sauce, finely mince dill pickle spears and place into a small mixing bowl. Otherwise, skip to step 4).
In the same small mixing bowl, combine mayo, onion salt and lemon juice. Mix well and set aside.
Prepare fillets by washing with cold fresh water and then drying fillets very well with a paper towel. Cut fillets into about 3 x 2 inch cuts and set aside.
Prepare batter by combining Almond Flour, grated Parmesan cheese, Bay Seasoning, garlic powder, red pepper powder, egg and Sparkling Water. Use a hand/stand mixer to mix (you can hand whisk, but batter won't be as airy).
Take a piece of fillet and dip into batter mix and set aside.
Pour enough cooking oil to cover half the fillets into a fry pan of choice (we use a cast iron pan) and heat oil up to 375F (if you don’t have a thermometer, just wait until the oil starts to lightly smoke, about 3-5 minutes).
Once up to heat, reduce heat to medium, carefully add coated fillets and cook for 1-3 minutes until golden brown. Flip and cook the other side for 1-3 minute until golden brown. Once done, transfer fillets to drying rack and leave for about 1 minute (if you don't have a drying rack, you can just place them on a plate with paper towels).
Once all excess oil has dripped off, transfer the fried fish fillets to a serving plate and serve with optional sauce.