In a small mixing bowl, mix the margarine, masa and sugar using an electric mixer until light and fluffy, about 1minute.
In a blender container, blend half of the corn with the water until smooth. Combine this mixture with the margarine mixture, stirring well. Add the remaining corn kernels, corn meal, baking powder, salt and milk. Mix well.
Pour the corn mixture into an 8x8-inch baking pan. Tightly cover with plastic wrap and steam by setting atop a medium saucepan of water on top of the stove.
Bring water to a boil and steam corn mixture for 1 to 1 1/4 hour (making sure to check to see if you need to add more water), until a toothpick inserted in the center comes out clean. Note: The pan must be tightly wrapped at all times.
Tomalito should have a smooth, moist texture. Makes 12 to 16 servings.