Cut the onion, tomato, potato, and carrot into bite-sized pieces.
Heat cooking oil in a pan and sauté the onion.
Add the potato and carrot, and stir-fry together.
Add the tomato and cook on low heat.
Pour in water and bring to a boil.
Add curry powder and stir well to combine.
When the ingredients are fully cooked and the curry thickens, turn off the heat.