1. In a saucepan over medium heat the oil and saute the onion until soft, about 2 minutes.
2. Stir in the rice and cook until toasted, about 3 minutes.
3. Add 1⅔ cups water, the plum tomato, tomato paste, salt and cumin. Bring to a boil.
4. Add the whole jalapeño. Cover and simmer for 20 minutes.
5. Remove from the heat and let sit for 5 minutes.
6. Discard the jalapeño and top with cilantro.