Heat 1 inch of the 3 cups of vegetable oil in a large skillet to 375 degrees F (190 degrees C).
In a large bowl, mix together 450 grams of chopped okra, 1 cup of chopped onion, 1 teaspoon of salt, 1/4 teaspoon of pepper, 1/2 cup of water, and 1 egg.
In a separate bowl, combine 1/2 cup of all-purpose flour, 1 teaspoon of baking powder, and 1/2 cup of cornmeal.
Stir the flour mixture into the okra mixture until well combined.
Carefully drop spoonfuls of the okra batter into the hot oil.
Fry each patty on both sides until golden, about 2 minutes per side.
Remove the patties with a slotted spoon and drain on paper towels.