Cook the millet in water, till it becomes moist and creamy.
Add the mashed bananas, the zest, the cinnamon and the salt. Let it cook for more 5-10 minutes until you get the texture you wish.
In a frying pan, toast the walnuts, with a pinch of salt.
Serve the porridge, adding the banana slices, the walnuts and a bit more of cinnamon sprinkled.