Start by soaking the raisins in warm water. Wash and peel the zucchini, then cut them into cubes.
Clean the celery stalk, depriving it of the external filaments, and cut it into slices. Clean the spring onion by discarding the first layer but keeping the green leaves; cut it into thin slices.
Pour the oil into a large non-stick pan and add the spring onion and celery. Turn on the flame and, as soon as they begin to fry, add a little water, about 2-3 tablespoons.
Cook for about 5 minutes, until the onion and celery are tender, stirring frequently. Let the majority of the water evaporate.
Then add the zucchini and let brown over high heat for a couple of minutes. Salt them and add the chopped basil and mint, the squeezed raisins, and the pine nuts.
Cover with a lid, lower the heat to medium intensity, and let the zucchini caponata cook for about 10 minutes, stirring occasionally. When the courgettes are tender, remove the lid and let the cooking juices reduce.
Raise the flame and add the sugar, and immediately after the vinegar. Mix carefully, always cooking over high heat for about a minute, until you no longer smell a strong vinegar smell. Then put out the fire.
Serve the sweet and sour zucchini caponata at room temperature as a side dish, or you can use it to garnish delicious bruschetta.