Mix sour (or coconut) cream, vinegar, garlic and season to taste with salt. Cut the fish across the grain of the flesh into strips roughly 1/2 inch wide, and add it to the cream marinade. Cover and refrigerate for two hours, though preferably overnight!
Make a batch of my keto tortillas. You can have them shaped and ready to go for cooking them simultaneous to the fish- as the secret to great tacos is eating them right away!
Prepare your frying station by adding enough oil to a skillet or pan to make it about 1/2-inch deep. You can save a lot of oil by using a narrower pan and frying in batches. Heat up oil over medium/low heat while you coat the fish.
Mix the whey protein, baking powder, chili powder and salt in a shallow plate or dish. In a second plate or dish, whisk the egg with cream and vinegar.
Coat the fish by lightly removing excess marinade, dipping in the egg mix, followed by the whey protein mix, immediately placing in the hot oil and basting the top right away. You want to fry the fish right after coating for best crispness. Fry on both sides until deep golden and transfer to a paper-lined plate for a couple minutes.
Serve right away with the freshly-made tortillas, plenty of limes and your salsa of choice.
*Or whip up your own chili powder mix: 3/4 tsp paprika, 1/4 tsp garlic powder, 1/4 tsp onion powder, 1/4 tsp dried oregano, 1/8 tsp cayenne pepper, 1/8 tsp dried cumin. Please note that nutrition facts were estimated for the fish only, add 2g net carbs per keto tortilla. Also, keep in mind that estimating a completely precise analysis for these is virtually impossible given the marinade, frying oil etc. Having said that, the fish and coating itself is virtually carb-less.