Briefly fry the onions in a large saucepan. Mix all ingredients together except for the water. Bring the water to the boil and add. Mix everything well.
Heat a pan with a little vegetable oil. Shape a patty from a heavily heaped tablespoon of the batter and fry on both sides in the pan.
If the patty sticks to the bottom of the pan or it cannot be turned, stir more oatmeal (or flour) into the batter.