In a medium, heavy saucepan, heat the lard over medium-high heat, add the chorizo and cook, stirring, for 1 minute. Add the onions and bell peppers, and cook, stirring, until soft, about 3 minutes. Add the garlic and cook for 30 seconds. Add the rice and cook, stirring, for 1 minute. Add the tomatoes and cook, stirring, for 1 minute. Add the stock, salt, and saffron, and stir well. Bring to a boil. Lower the heat to low, cover, and cook undisturbed until all the liquid is absorbed, about 20 minutes.

Remove from the heat and let sit, covered, for 10 minutes. Uncover and fluff the rice with a fork. Add the oregano and cilantro, and stir to incorporate.

Turn into a decorative bowl and garnish with the green onions. Serve immediately.