Remove the husks from the corn, and, using a sharp knife, cut the kernels from the cob from top to bottom and gather the kernels with their juices in a large bowl. Use the back of a knife to scrape the residual corn from the cobs. Repeat with the remaining corn. Set the corn cobs aside because we'll be using them later.
Using a food processor or blender, pulse the corn with a cup of water until coarsely ground. You do not want to puree the corn.
In a bowl, combine the mixture with cornmeal, salt, and palm oil.
Finally, add the chopped spinach and set aside.
Cut the banana leaves into rectangles, remove any ugly edges, submerge them in water to clean, drain, and pat dry. Use plastic wrap if banana leaves are not available.
The leaves must be heated and wilted over an open high flame to make them flexible.
Then, cut the aluminum into large squares or rectangles and place a piece of the leaf or saran wrap on it. Repeat the process and set them aside.
Place about a cup of the koki corn mixture on the leaf.
Then quickly fold aluminum over it and press sides into a rectangle shape, pressing inwards so none of the koki runs out.
Then fold the sides twice in to seal. Repeat the process and set them aside.
Place the koki corn tamales in the pot with reserved cobs.
Line the bottom of a large stock pot with reserved cobs. Add enough water to almost but not quite submerge the cobs. Cover the cobs with a layer of aluminum foil. The koki corn should not come in contact with the water so they don’t get soggy. You just want to steam them.
Cover them with more banana leaves or foil. Steam them for about an hour minutes, checking occasionally to make sure you have enough water in the pot.
Turn off the heat, take the koki corn bundles out, and let them rest for about 10 minutes. Unwrap and enjoy.