1: Chop the tomatoes into 1cm cubes, finely dice the red onion and chilli, and grate the garlic.
2: Slice the olives into 3 slithers each and roughly chop the basil leaves.
3: Heat 1 tablespoon of olive oil in a large saucepan and sauté the onions until soft but not brown, about 5 minutes.
4: Add the garlic and chilli to the saucepan and cook for 1 minute.
5: Stir in the tomato paste and then add all the chopped tomatoes and their juice, cooking until soft and mushy.
6: Smoosh the mixture to resemble a thick sauce.
7: Pour in about a cup of water, bring to a boil, and let simmer for about 10 minutes.
8: After 5 minutes, add the capers, olives, and basil leaves.
9: In a separate pot, boil water and cook the spaghetti until al dente (about 8 minutes).
10: Reserve some pasta water and add it to the sauce to loosen it.
11: Taste and season the sauce with salt and pepper.
12: Drain the pasta and mix it in the sauce so each strand is covered.
13: Top with more basil leaves and serve hot.
