Cut the banana in half lengthwise then cut each half into 2 pieces. You should end up with 4 slices.
Heat a nonstick pan over medium-high heat. Add a teaspoon of oil. Place the bananas flat-side down and fry until brown, about one minute. Transfer the bananas to a stainless steel pan (or anything that can withstand the heat of the flames), cooked side up.
Spoon the sugar evenly over the bananas, making sure not to leave any empty spots.
Using the blowtorch, sear the sugar until it caramelizes and turns brown. Try to keep the flame moving at all times and be careful not to burn the sugar. They cook fast!