I didn't really know the recipe and although it's easy to find on the internet, I was just too lazy to follow such recipe.
So I just used my feeling, hahaha. I took all-purpose flour, mixed it with an egg, a can of sweet corn, and half-pack of roerbakmix (mixed diced vegetables), some water, a bit of salt, a bit of sugar, a bit of chicken powder, and tadaaaa:
They tasted good, although what I had in mind was somewhat more crispier (eh, what's the correct term again? maksudnya sih renyah, garing). I reckoned the egg made them puffier (lebih empuk2 gitu. Enak sih, tp jadi kayak bala2/bakwan).So, I tried one more time, after coming back from Christmas Celebration in Wassenaar this afternoon. This time, I didn't use egg, but I added some portion of cornstarch (tepung maizena) to the all-purpose flour. The rest of the ingredients were the same (oh, I added garlic and white pepper a bit). Here goes the result (after some of them were eaten, hahaha):

They were indeed crispier. I still have some doubt whether they will stay crispy after some time tho. If they're not, I will consider removing the mixed vegetable from the ingredients next time like how it's supposed to be in the first place (hey, they're Perkedel Jagung you know), hehehe