Make the batter: sift rice flour, baking soda, sugar, and salt together in a mixing bowl. Then add sesame seeds and grated coconut. Gradually add water while whisking. Stir until fully incorporated.
Heat oil to 350°F. Slice bananas lengthwise and set aside.
Place banana slices into the batter, and make sure each slice is thoroughly coated. Fry only a few slices at a time. Occasionally flip them over to ensure even frying. Once golden brown and crispy, drain on paper towels. Best when served immediately.