Into a wok or frying pan, pour enough oil to reach a depth of at least three inches and turn on the stove to start heating it.
Place the sugar in a wide shallow bowl.
Make the batter by whisking together the egg, flour, salt, baking powder and milk until smooth.
Peel the bananas. Cut each vertically into three to five slices, depending on how large they are, without going all the way through on one end. Carefully spread the slices to make a "fan".
Dip each banana in the batter making sure that the batter reaches the crevices between the slices.
Over medium heat, fry the battered bananas, two to three minutes per side, or until golden and crisp. Do this in batches to avoid overcrowding.
Scoop out the cooked bananas, dredge in sugar and serve at once.