• Put a large pot of water on to boil for pasta. Add salt once it starts to boil and bring to the boil again 

In the meantime make the sauce.

• Wash the capers well if they have been preserved in salt. Peel and chop the garlic finely. Cut the olives into small slices. Wash the tomatoes and cut them in half. Remove the seeds from the peperoncino and chop into small pieces.
• Heat the olive oil over a medium heat in a deep frying pan or skillet. Add the garlic and the tomatoes. When they start to soften, add the capers, the olives and the finely chopped chili pepper. 
• Season with a little salt (not too much because the olives and capers are already salty) and cook for 10 minutes to reduce the sauce but without losing the fresh flavour of the ingredients.
• Cut the tuna into chunks and chop the parsley. Turn up the heat and add the tuna and parsley to the sauce and cook for another 2 minutes. The tuna must remain a bit pink. 

Finish the dish

• Cook the pasta al dente according to the instructions on the packet., Save a little of the pasta cooking water. Then drain the pasta and put it in the pan with the sauce. Mix everything together well, adding a little pasta cooking water if the sauce seems dry. Serve immediately sprinkled with a little chopped parsley.