In a bowl, mix flour, cornstarch, and baking powder. Add water and stir until smooth. Peel and core apples; cut each apple into 3 wedges. (If you use bananas, peel and cut in 1/2 inch thick diagonal slices.) Place fruit in batter and turn to coat evenly. Into a deep pan pour oil to a depth of about 1 1/2 inches. Heat oil to 350 degrees. Using chopsticks or a spoon, lift one piece of fruit at a time from batter and let excess batter drip off, then lower fruit into hot oil. Cook several pieces at a time until coating is golden brown (about 2 minutes). Remove with a slotted spoon and drain on paper towels. Generously oil a flat serving dish. Fill a serving bowl to the brim with ice cubes; cover with water. Place sugar, water and oil in a ten inch frying pan; stir to blend. Place pan over high heat. When mixture begins to bubble (about one minute), shake pan continuously to prevent burning. Continue cooking and shaking pan until syrup just turns a pale straw color (about 9 minutes). Immediately remove from heat, add sesame seeds, and swirl to mix. (Syrup will continue to cook after you remove it from heat and color will turn golden in a few seconds.) Drop fruit into syrup and swirl to coat evenly. Using two spoons, immediately remove each piece of fruit and place on oiled dish so pieces do not touch. At table, dip each piece of fruit in ice water so coating hardens and fruit cools. Serve.