Preheat a convection oven to 93°C / 200°F. Line a sheet pan with silicone paper and spray with nonstick cooking spray.
Cut the bananas into 1.75-cm / .5-in disks on the bias. Do not use very ripe bananas since they will not be able to cook properly (they will fall apart as soon as they start cooking).
In a large sauté pan, mix the sugar, water, and lemon juice until all the sugar is moist and has a wet-sand consistency. Make sure there are no sugar crystals along the inside of the pot and that all the sugar has been hydrated.
Cook the sugar over high heat until it reaches a medium amber color, about 8 minutes (this time will vary depending on the type of burner used: induction will be faster than gas or electric).
Place the bananas in the caramel. Put the sauté pan in the convection oven and turn each banana slice over every 20 minutes. Do this a few times until the caramel has reached a dark amber color and the bananas are cooked through and appear caramelized, about 1 hour.
Transfer the bananas to the prepared sheet pan, using a slotted spoon so that the excess sugar drips off before putting the bananas on the sheet pan.
Let the bananas cool to room temperature. Reserve covered with plastic at room temperature during service. Discard leftover bananas after service.