Prepare the calamari by removing the heads, tentacles and wings. Keep the calamari tubes to one side and discard the heads. Finely chop the tentacles and wings.
Heat a little olive oil in a frying pan and sear the chopped calamari quickly with a splash of wine and season with salt and pepper.
In a mixing bowl, combine the cooked calamari with the rice, sultanas, fennel, capers, zest, eggs, breadcrumbs and cheese. Mix well to form a soft stuffing. Add more seasoning and cook a little of the mixture to taste if you feel unsure about the seasoning.
Fill each calamari tube with stuffing, leaving a little space at the open end for the stuffing to expand. Secure the ends with toothpicks.
Heat the tomato sauce in a medium-sized saucepan. Add the stuffed calamari and cook gently until tender, 30–40 minutes.
Towards the end of the cooking time add the tomatoes to give texture and freshness to the sauce. The calamari themselves do not have great flavour; it is the combination of rich tomato sauce and tasty stuffing that makes the finished dish interesting.