Put the gnocchi in boiling salted water, let them steep for about 2 minutes and drain. Peel and finely chop the onion. Heat the oil in a pot. Sauté onion in it, sprinkle with sugar and caramelize, deglaze with vinegar and tomatoes, season with salt and pepper.
Let simmer for about 5 minutes.
Wash the basil, shake dry and pluck the leaves from the stalks. Add gnocchi to the tomato stock, mix and arrange in bowls.