To make the batter: Cut the kernels from the ears of corn (you should have about 1 1/2 cups) and place them in a medium bowl with the onion. Add the salt and baking powder, followed by the flour and cheese. Toss until well coated, adding more flour if needed. Crack in the egg and stir to combine. You might question if the batter will hold together, I assure you it will. 

To make the fritters: Heat a ¼-inch layer of sunflower oil in a medium skillet over medium heat. When the oil is hot, spoon the batter into four scoops into the hot oil. Press down with the back of the spoon to flatten the fritters. Fry until the fritters are a deep golden, 3-4 minutes per side. Repeat with remaining batter. 

Give a swoosh of the mayo in the bottom of two bowls and top with the corn fritters. Toss the thinly sliced radish with the olive oil and salt, then finish the fritters.