Slice the bananas lengthwise into 2 or 3, according to the desired thickness.
You may cut each slice into two if you wish.
Take the flour, salt, sugar and turmeric powder (if using) in a bowl.
Add just enough water to form a batter. It should not be too thick or too runny.
Meanwhile heat oil for deep frying.
Tip in the banana slices into the batter so that a coating is formed over it.
When the oil is hot, drop the batter-coated slices into the hot oil.
Fry till golden brown on both sides.
Drain onto an absorbent paper.