Heat olive oil in a saucepan and sweat the chopped onion and garlic cloves in it until translucent. Add the tuna and fry (but do not brown). Add the diced tomatoes and the canned tomatoes and let everything simmer for about 45 minutes, stirring occasionally (the tomato peel can be removed if necessary).
Season to taste with the stock cube and the spice mixture (I always have mine from Italy, you can get it there in Italian supermarkets. Be careful if there are chilli peppers in them - it is very spicy). Let simmer for another 5 minutes, season again if necessary.
Let the sauce simmer for 1 to 1.5 hours on a low level (only then does the typical taste of the sauce develop.
Just before the end of the cooking time, put the pasta on and cook according to the instructions on the package until al dente.
Arrange the pasta in portions on plates, pour the sauce over it and sprinkle with freshly grated parmesan.
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