peter wrote:
I'm trying to make an ethic snack that somewhat resemble waffle but is eaten
without jam or fruit.
The ingredient for the batter are flour, sugar, baking powder, milk, eggs,
corn starch, water, oil.

I also have a corresponding cast which is just two pieces of cast iron with
concave holes in them. It was bought from another country.

After I pour the batter into this cast and heated it up, the cooked batter
sticks to the cast like crazy. I already brushed some oil in the cast. What
else can I do to make cast iron less sticky? They don't make non-stick
version.

You are on the right track with seasoning the cast iron with oil.

http://kitchen.apartmenttherapy.com/...st-iron-006719