Place a large pot with water on high heat and bring to the boil. Add a pinch of salt and spaghetti pasta to the boiling water and cook until ‘al dente’ – refer to the cooking time specified in pasta packet instructions.
Meanwhile heat the olive oil in a large non-stick frying pan over medium heat. Add the onion and chilli. Cook for a few minutes, stirring, or until the onion softens.
Add the tuna to the frying pan and cook for 2 minutes. Then add the capers and chopped tomatoes and cook for 10 minutes. Season with salt and pepper to taste and mix well with a wooden spoon, cooking for a further 2 minutes.
Drain the pasta, reserving 1 tablespoon (20ml) of the pasta cooking liquid. Add the pasta and reserved cooking water to the frying pan with tuna sauce and toss well over the heat for 1 minute to soak up lovely flavour, then remove from the heat. Add the parsley and toss to combine. Divide the pasta among serving bowls. Add the finishing touch by sprinkling freshly torn basil leaves on top – Buon appetito.