Cut the ready-to-cook squids into small pieces. Finely dice the onions and garlic. Heat the oil in a saucepan and briefly fry the squids. Add the onions and garlic and sweat briefly.
Strain the tomatoes through a sieve into the pot. Add the olives and capers. Top up with the meat stock and the white wine. Season with salt, pepper and sugar and cover and cook over a medium heat for about 1 hour. Then add the peeled, pitted and diced tomatoes. Stir the chopped tarragon into the sauce, bring to the boil again and serve.