Steps
1. Heat up a pan over high heat.
2. Add the mackerel fillet and sauté for 2-3 minutes.
3. Add the onions and peppers and continue to sauté until softened, about 5 minutes.
4. Add the cooked white rice and tomatoes and season with salt and pepper.
5. Add enough stock or water to cover all the ingredients, bring to a boil and then reduce to a simmer.
6. Simmer for 15 minutes until the mackerel is cooked and serve hot.