Pour the buttermilk into a bowl. Season the fish pieces with salt and pepper and then soak them in the buttermilk for about an hour - this will do really nice things to the fish's texture
Make your salsa: Put your corn into a hot dry grill pan and lightly char it all over, about 20 minutes, this will really bring out the flavor and sweetness of the corn. Remove the corn to a plate and let it cool a bit, then carefully run a small sharp knife from top to bottom to remove those beautiful kernels of corn. Discard the cobs and put the kernels into a bowl with all the other salsa ingredients and a pinch of salt, pepper and paprika. Stir it all up and have a taste to get the seasoning right - you want heat from the chile, freshness from the mint, and salt to cut through it all
Get a large, sturdy, deep saucepan over high heat, pout in your vegetable oil, and heat it to around 350 F. If you don't have thermometer, put a small piece of potato, and when it rises to the top and turns crispy and golden, you know the oil is ready
Put your cornmeal or flour onto a large plate and add a good pinch of salt and pepper. Take a piece of fish out of the buttermilk and let the excess drip off, then roll it in the cornmeal or flour. Do the same thing with all of the fish, then carefully lower it into the pan of oil using tongs or perforated spoon. You may need to fry the fish in batches
Deep-fry the fish for 2 to 3 minutes (depending on how big your fillet is), until golden, crisp and brown. Do not overcook your fish or it will be tough just like any other seafood
Remove the fish to a plate lined with paper towels and sprinkle with sea salt. As soon as the last batch is ready, divide most of your salsa between your plates, pop the pieces of fish on top, and finish with a touch more salsa. Serve with arugula or a crisp green salad if you have, and wedges of lemon if you like