Cook the pasta in 3-4 l boiling salted water (1 teaspoon salt per litre) according to the instructions on the packet.
Drain the corn in a sieve. Peel and halve the onions and cut them into fine strips. Pour oil from a tuna can into a pan, heat it up and fry the onions in it. Stir in tomato paste and sauté briefly.
Add tomato sauce, rinse the glasses with a little water and add the contents. Add corn and capers, bring to the boil and simmer for 4-5 minutes.
Grate parmesan. Pour the pasta into a sieve, drain and put it back into the pot. Season tomato sauce with salt, pepper and 1 pinch of sugar. Fold in tuna. Add the sauce to the pasta and mix.
Make noodles. Sprinkle with parmesan.