Toss the okra with the buttermilk in a bowl until every cut surface is wet.
Combine the cornmeal, flour, 1 tsp salt, black pepper, paprika and cayenne in a wide dish.
Lift the okra from the buttermilk with a slotted spoon, toss it through the cornmeal mixture and let it rest on a tray for 10 minutes.
Heat the oil in a heavy pot to 365°F and set a wire rack over a sheet pan.
Shake off loose coating and fry the okra in four small batches until crisp and golden, 2 to 3 minutes per batch.
Let the oil return to 365°F between batches so the crust does not soak up grease.
Drain the okra on the rack, season with the remaining 1/4 tsp salt and serve immediately.