Put the rice into a bowl and cover with very hot water. Stir once and leave to soak for 10 minutes. Drain, rinse in cold water, and drain again.
Heat the oil in a heavy pan. Give the rice a final shake and stir into the fat. Fry over medium heat for about 5 minutes, stirring almost continuously. Add the onion and garlic and continue frying until the rice is just turning a pale gold and the onion is transparent - about 3 to 5 minutes longer.
Pour in the broth and add cumin and salt to taste , stir once again for the last time, and cook over fairly high heat, uncovered, until all the broth has been absorbed and air holes appear in the surface. Cover the surface of the rice with a towel and lid and continue cooking over very low heat for 5 minutes more. Remove from the heat and set aside in a warm place for the rice to absorb the rest of the moisture in the steam and swell, about 15 minutes. Dig gently to the bottom and test a grain of rice. If it is still damp, cook for a few minutes longer. If the top grains are not quite soft, then sprinkle with a little more hot broth, cover, and cook for a few minutes longer.
Before serving, turn the rice over from the bottom so that the flavored juices will be distributed evenly.