Cipolline in Agrodolce (Sweet-and-Sour Onions)

The combination of sweet and sour isn’t common in Italian cooking, but it’s essential to certain preparations, and I’m fascinated by it, probably because my own cooking tends to be strictly savory, apart from dessert. In fact, these cipolline in agrodolce, which go well with meats and poultry, are mild enough that you can eat them as a vegetable. (For a…