1Place the bell peppers preferably over the hot coals of a grill or over the direct flame of the kitchen stove (cover the bottom plate with aluminum foil) and grill, turning with kitchen tongs as the sides blacken, until the skin is lightly charred, 2 to 3 minutes.
2Transfer to a bowl, cover with plastic wrap or foil, and set aside to cool, about 5 to 7 minutes.
Peel off only the highly charred skin.
3Discard the stems and seeds and chop the peppers coarsely.
Strain and save any juices that may have accumulated in the bowl.
4Heat the oil in a large nonstick saucepan over medium-high heat and cook the onion, stirring until golden, about 5 minutes.
5Add the garlic, rice, coriander, and cilantro and cook over medium heat, stirring carefully, until golden, about 5 minutes.
6Add the water, salt, and any juices reserved from the peppers and bring to a boil over medium-high heat.
Reduce the heat to low, cover the pan, and cook until all the water has been absorbed and the rice is tender, 12 to 15 minutes.
7Gently mix in the grilled peppers, cover the pan, and allow the rice to rest undisturbed about 5 minutes.
Transfer to a serving dish, fluff with a fork, garnish with the scallion greens, and serve.