Begin by drying the cod fillets with paper towels—this step helps the coating stick better during frying.
In one shallow bowl, mix together the flour, cornmeal, garlic powder, onion powder, paprika, salt, black pepper, and a pinch of cayenne. In a second bowl, whisk the eggs and buttermilk until smooth.
Heat a few inches of vegetable oil in a deep skillet or fryer over medium-high heat. To check if it’s ready, drop in a bit of the flour mixture—if it sizzles, you're good to go.
Dip each cod fillet into the buttermilk-egg mixture, then dredge it through the seasoned flour blend. Press lightly so the coating adheres well.
Carefully lower the coated fillets into the hot oil, one at a time. Don’t crowd the pan. Fry for about 4–5 minutes per side until the crust is golden and crispy. Once done, transfer the fish to a paper towel-lined plate to drain any excess oil.
While the fish rests, toast your sandwich buns in a skillet or on the grill for extra flavor.
To build the sandwiches, spread tartar sauce (or your favorite sauce) on the bottom bun. Place a crispy cod fillet on top, then add lettuce and tomato if desired. Finish with the top bun and serve right away, with lemon wedges on the side for a bright, fresh touch.