Add the edamame, jalapeño, onion, garlic and water to a small blender. Blend until completely smooth.
Put a large pan on medium heat, add the cornmeal and the edamame mixture to the pan and stir to combine. Make sure there are no clumps.
Stir continuously as the cornmeal comes to a simmer. It will begin to thicken in the first few minutes. Continue to cook for 5 minutes, the polenta will continue to get creamier and creamier.
Turn the heat down to medium-low. Add water as needed and continue to cook for another 5-8 minutes, or until you can no longer taste any graininess in the cornmeal.