In a medium bowl, toss the cabbage, cilantro, 1/4 cup salsa and salt to taste. In a small bowl, stir together the sour cream and remaining 3 tablespoons salsa. Set both aside.
In a shallow dish, whisk together the cornmeal and 1 tablespoon salt. In another shallow dish, beat the eggs with a fork. Coat the fish slices in the cornmeal, then in the egg, then in the cornmeal again, and place on a plate.
In a medium cast-iron or other heavy skillet, pour the oil to a depth of 1-1/2 inches and heat over medium heat until the surface ripples, about 2 minutes. Add about a third of the fish slices to the skillet and cook, turning once, until golden, 3 to 4 minutes. Transfer with a slotted spoon to a paper-towel-lined plate. Repeat with the remaining fish slices.
In a large skillet, warm the tortillas on both sides over high heat. Spread about 1 teaspoon sour cream sauce on a tortilla, then top with a few pieces fish and a heaping spoonful of the slaw and fold over. Repeat with the remaining tacos.