If the lentils are not already cooked, rinse them and simmer them in water until tender, then allow them to cool completely. Slice the banana into chunks and freeze it if it is not already frozen to create a thicker smoothie texture.
Pour the milk into the blender first. Then add the frozen banana pieces, cooked red lentils, cocoa powder, and maple syrup. Placing the liquid ingredients at the bottom helps the blender process the thicker ingredients smoothly.
Blend the mixture on high speed for about 45–60 seconds until the smoothie becomes creamy and completely smooth. If you prefer a thicker, colder texture, add ice cubes and blend again briefly.
Pour the smoothie into a tall glass and serve right away. For presentation, you can sprinkle a small amount of cocoa powder on top or garnish with a banana slice.
