Cipolline all’agro Dolce

This is one of my favorite vegetable dishes and is traditionally made using those marvelous flat little ready-peeled button onions which you can so conveniently buy in Italy. If you can’t find these onions (called borettane) you can use pearl onions or small shallots instead. You can use less or more vinegar for this recipe, partly because of personal taste, but also because I find the acidity level in good-quality vinegar sometimes varies wildly.