Line 6 ramekins (6-oz/175-ml) with parchment paper.
Bring the water of the steamer to a boil (the amount of water should be enough for 25 minutes of steaming).
Mash bananas with fork, set aside.
Whisk together eggs, sugar and salt in a mixing bowl until combined.
Combine 1000 ml of water with 400 ml of hot water in a large steel bowl to yield 45°C/113°F of warm water.
Place the mixing bowl in warm water, then whisk the egg mixture over medium speed until stiff. (Reminder: You need to stop for a few times during this process to avoid overheating of the equipment.)
The egg mixture is stiff (the ribbons formed by egg mixture will stay on surface for a while before dissolving slowly).
Add evaporated milk and corn oil to mashed bananas, mix well.
Add ½ portion of beaten eggs to banana mixture, mix until combined.
Whisk together flour, baking powder and baking soda, then sieve into banana egg mixture, mix until combined.
Add in the remaining beaten eggs, mix gently using hand whisk.
Fold the batter gently until well combined using spatula.
Pour the batter into lined ramekins, tap a few times on counter top to burst large bubbles.
Steam over high heat for 25 minutes.
Steamed banana cupcakes are ready to be served!