Heat the oil in a large cast-iron pot or 6-quart saucepan. Add the sofrito and onions and cook until the onions are soft, about 6 minutes. Add the pigeon peas and saute for 2 minutes. Add the rice and sazon con achiote and cook until the rice is lightly browned.
Add the chicken stock, bring the mixture to a boil and then reduce the heat to medium low. Cover and cook until the rice is tender, about 30 minutes or longer depending on how soft you like your rice. Season with salt and pepper and serve.
Combine the assorted peppers, cilantro, parsley, olive oil, vinegar, garlic, onions, green and red bell peppers and serrano peppers in the bowl of a food processor and puree, stopping occasionally to scrape down the sides of the bowl, until a coarse paste forms, about 1 minute.
Sofrito can be refrigerated up to a week and kept frozen for up to 3 months.
Recipe courtesy of Kelis Rogers