Fry the onion gently in oil in a large pan for 10 minutes until soft and translucent. Add the garlic and fry for 2 minutes. Add the tomato purée and vinegar. Stir for 1 minute. Add the tomatoes and sugar. Cover and simmer for 1 hour.
Make the tapenade: it’s easiest to blitz the olives, capers, anchovies, garlic and thyme in a food processor, then add the parsley, lemon juice and just enough oil to make a rough paste. Season to taste (you’ll need little or no salt).
Blend the soup in a processor until smooth. Strain through a sieve, then return to the pan. Mix the cornflour with 1 tablespoon of water to make a paste. Add to the soup, with the bay leaf and stock. Season, then simmer for 15 minutes. Check the seasoning.
Spread a little tapenade onto toasted ciabatta, sprinkle over a little extra parsley, then serve with the soup.
If you like, you could add a swirl of cream or crème fraîche to this to make a cream of tomato, but I like the fresh flavour as it is. Tomato soup can be quite sweet, so the salty tapenade is a good foil.
This will make more tapenade than you will need, but it’s not worth making less, and it’s very moreish anyway!