Clean and chop the vegetables.
Clean the bonito and chop into cubes. Set aside the skin and fish bones.
Season with salt and pepper and let settle.
Boil the skin and fish bones with onion and 2 or 3 laurel leaves to make a fumet.
Meanwhile, fry the peppers and set aside.
In the same oil, fry lightly the onion.
Add the chopped potatoes, the tomato sauce and fumet until cover them completely.
Simmer until the potatoes are ready to be eaten.
Add the bonito and the peppers, and remove the pan from the heat.
Let settle for 5 minutes before serve.