Zucchini carpione (cooked with vinegar)

Finely slice some onions and cook them over low heat in a casserole with extra virgin olive oil and salt to taste. Once browned, add the zucchini cut into pieces, without their core and seeds. When the zuccchini have finished cooking in the casserole over a low heat, add some pieces of bread soaked in the vinegar. Leave on the heat for a further 10/15 minutes, adding, if necessary, a little warm water so that the mixture remains quite soft. Serve hot.