1. Place a pan of salted water onto a high heat and bring to the boil.
2. While the water boils we’ll make the sauce… Put a saucepan on a medium heat and add the sliced onion along with a good pinch of salt. Cook gently over a medium-low heat, without colouring, for 6-8 mins (or until the onion is completely cooked and has softened).
Add in the finely grated/chopped garlic and cook for a further 2 mins. Stir regularly so the garlic doesn’t burn.
3. Add the chilli flakes and some freshly ground black pepper, followed by the tomato passata. Bring to a simmer, then turn down the heat to low while we cook the pasta.
4. Add the pasta to the boiling water and set a timer for 2 mins less than the packet suggests for ‘al dente’.
5. While the pasta cooks, add the capers and olives to the sauce. Stir through.
6. Just before the timer goes off for the pasta, add the tuna (in chunks) to the sauce. Be careful not to break the tuna up too much.
7. Using tongs, transfer the pasta into the sauce and turn up the heat. Stir the pasta through, or toss the pan and leave to cook for a further two mins. Add a little extra pasta-cooking water as you go until your sauce gets a velvety consistency.
8. Pop in the chopped parsley and a squeeze of lemon juice. Stir through gently, transfer to warmed plates, and drizzle of some extra olive oil. Feast.