1Place onions, chiles, garlic, cilantro and 1 cup stock in a blender. Blend, strain and season with salt and pepper.
Rinse and drain rice. Heat oil in a heavy pot over medium-low heat. Add rice and sauté, stirring constantly, for 2 minutes. Add sauce and remaining 1 cup stock. Cover and simmer for 20 minutes. Remove pot from heat, but keep covered, allowing rice to cook for another 10 minutes.