Rinse the rice really well by placing in a dish, fill with water, swirl with your hands and draining the water. Repeat until the water is clear. Drain well.
In a blender, process the tomato, onion, garlic and salt until smooth.
Heat the vegetable oil over medium heat in a saucepan and add the rinsed and drained rice. Lower the heat and cook, stirring often, for 10 minutes. The rice may clump together, this is fine. It will be squeaky and will have a white, shiny appearance after 10 minutes.
Increase the heat to high, add the tomato mixture and stir until the most of the liquid has been absorbed. Add the boiling water, stir and add the coriander, turn the heat to low, cover and cook for 10 minutes.
Turn the rice with a large spoon to redistribute, and cook for a further 7 – 10 minutes. Once cooked, turn off the heat and allow to stand, covered for a further 10 minutes. Fluff with a fork and serve.