In a medium bowl, whisk together the flour, baking powder, salt, coriander and cayenne. Mix in the egg followed by the beer to form a smooth batter.
In a 4-quart Dutch oven, heat 2 inches of vegetable oil to 375º and line a plate with paper towels. Working in batches, dip the pickle slices into the batter, then slowly drop into the oil. Cook until golden brown, 2 to 3 minutes. Using a slotted spoon, transfer the pickle chips to the prepared plate to drain. Immediately season with kosher salt. Transfer to a platter and serve.