Preheat the oven to 200°F(95C°). Line baking sheet with parchment paper.
Squeeze the lemon and set aside.
Peel the bananas, slice them into almost ⅛ (3mm) thick slices. Dip the slices into lemon juice. Then place them on the baking sheet covered with parchment paper.
Bake for 1 and ½ hour until they shrink, become less sticky and chewy. Remove the baking sheet from the oven and flip them over. Place the baking sheet to the oven again and bake for extra 45 minutes, until they are crispy at the edges and chewy in the middle. Keep them in the turned off oven for 15 minutes. They will become crispier at the edges as they cool. The baking time may vary from oven to oven, so you should check them. If you want to eat them all crispy, you need to bake for additional 30-45 minutes.
The calorie information above is an estimate that is provided by an online nutrition calculator.