Rinse the rice well in a sieve under running water and set aside to drain.
Put the spinach, cilantro, and 2 cups (480 ml) water in a blender and puree until fairly smooth.
In a 2-quart (2-L) saucepan, heat the oil over medium-high heat. When it shimmers, add the garlic and cook, stirring, until golden, about 1 minute. Add the rice and stir for 30 seconds, then add the salt and the spinach mixture, scraping as much of it from the blender as you can. Stir well and bring to a boil over high heat. Stir again, cover, and cook on the lowest heat for 15 to 20 minutes, until the rice is tender (check after 15 minutes; much of the spinach will have floated to the top, but that’s fine—just dig a few grains out with a fork to test them). Remove from the heat and let stand for 3 minutes, then fold and fluff with a spatula or fork and serve.