Put the oven on a pre-heat of 200 C.
Put the peppers, garlic and onion in a roasting tin. Drizzle some oil over them and then toast them for 45 minutes. Take them out. Separate the pepper in to a small bowl and cover with plastic cling film. When they cool down, cut them in to thin strips along with the other vegetables.
Bake the mackerel fillets now. Put them on a baking sheet, drizzle some oil and bake for around ten minutes.
In the large serving bowl, place the mackerel, onions, garlic and peppers. Add the remaining oil. Season with salt and freshly ground pepper. Garnish with the bay leaf. Refrigerate for an hour and then you are all set to present it with pride.The vibrant colors of the Peppers make it more attractive.