The rice gets its color from chopped cilantro and poblano chiles.
Heat oil in a large saucepan over medium heat. Add onion; cook until it is soft and translucent, about 8 minutes. Add garlic; cook 2 minutes. Add rice, and stir to coat. Add stock, and bring to a boil; reduce heat to a simmer. Cover, and cook until rice is tender, about 15 minutes.
Turn off heat; let stand, covered, until liquid is absorbed, 5 to 10 minutes. Fluff with a fork; stir in cilantro and poblano. Season with salt and pepper. Serve hot.