In a large wide saucepan, heat oil over medium heat. Add onions, peppers; stir and cook until softened, about 5 minutes. Add tomatoes and garlic and cook, stirring, for 5 minutes. Add rice and stir for 1 minute to coat the grains. Pour in chicken stock and bring to a simmer. Add salt, cayenne pepper and reserved black-eyed peas. Cover and simmer on low heat for about 20 minutes, or until liquid has been absorbed.