1Heat a good drizzle of olive oil in a large sauté pan. Add the onion with a pinch of salt and cook over medium heat for 5–7 minutes until soft and sweet.
2Stir in the garlic and chilli flakes and cook for another minute until fragrant.
3Add the red pepper, cherry tomatoes, capers, and olives.
4Cook for 5 minutes until the tomatoes start to break down and everything is glossy and softened.
5Stir in the tomato purée and cook it out for 1 minute to deepen the flavour.
6Pour in the passata, then add the drained tuna and balsamic vinegar.
7Season well and let the sauce simmer gently for 10–15 minutes until rich and thickened.
8Tear in fresh basil just before serving.
9Meanwhile, cook the pasta in well-salted boiling water until al dente.
10Roughly chop the feta with the basil, parsley, lemon zest, and juice until crumbly and herby.
11Toss the drained pasta into the sauce, loosening with a splash of reserved pasta water if needed.
12Divide between bowls and top generously with the herby feta.