Combine the broth and chiles in a medium saucepan, bring to a boil, and then partially cover and simmer gently over medium to medium-low heat for about 10 minutes. Pour the chile mixture into a food processor, add 1/4 cup cilantro and process to a smooth puree. Season with salt and keep warm.
Wipe the pan clean, add the oil, and heat over medium-high heat. Add the onions and cook until soft. Add the garlic and cook for 1 minute. Stir in the rice and cook for 1 minute. Add the warm broth mixture, stir, and season with salt. Bring to a boil, cover, and then reduce the heat to medium-low and cook for 15 minutes. Remove from the heat and let sit for 5 minutes, covered. Fluff with a fork, transfer to a bowl, and stir in remaining cilantro.
