Soak peeled beans in water for about an hour to overnight to completely hydrate them and facilitate blending.
Cut 6 pieces of aluminum foil large enough to wrap the finished koki, and set aside.
Cut the banana leaves into rectangles, remove any ugly edges, submerge them in water to clean, drain, and pat them dry. Use parchment paper if banana leaves are not available.
Heat the leaves and wilt them over an open high flame to make them flexible.
Chop the onions and habanero, and set aside.
Lightly warm palm oil in a small skillet or saucepan for about a minute or two until completely melted.
In a food processor or blender, puree the beans, onions, and habanero pepper with a cup of water or more until it reaches the desired consistency. (Do a test with your fingers; it should feel just a little gritty.) You may have to do this in two batches.
Pour the mixture into a large bowl; add palm oil, spinach. Mix everything together, then, season to taste with Maggie and salt. Make sure you have used up all the water.
Place a scoop of koki bean mixture on a leaf (about 2 cups). Then quickly fold them together to form a little purse, and set aside while you repeat the process until all the kokis are assembled.
Line the bottom of a large stockpot with aluminum foil or the remaining leaves or stalks to create a steamer. Add enough water to steam.
Steam cook koki for about an hour and 30 minutes, adding water as necessary to prevent burning.
Remove and let them cool for about 10 minutes, then serve.