In a large pot, bring 3 cups (720 ml) of water to a boil. Reserve the remaining 1 cup (240 ml) of water for later.
In a separate bowl, mix the cornmeal with the reserved 1 cup (240 ml) of cold water. Stir until it forms a smooth paste without lumps.
Gradually add the cornmeal paste to the boiling water, stirring constantly with a wooden spoon or whisk to prevent lumps from forming.
Continue to stir the mixture as it thickens, cooking over medium heat. The posho will become thick and smooth.
Reduce the heat to low and continue to cook for about 10-15 minutes, stirring frequently, until the posho pulls away from the sides of the pot and is fully cooked.
If the mixture becomes too thick, you can add a little more boiling water to reach the desired consistency.
If desired, add 1/2 teaspoon of salt to the posho and stir well.
Remove the pot from the heat and let the posho cool slightly.
Scoop the posho onto a serving plate or into a bowl.
Enjoy your meal!